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1982 22R will NOT start cold without starter fluid in carburetor. Once started she runs like a champ! How can I fix this starting issue?


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I have an 82 5 speed Sunrader with the 22R with 60,000 original miles and it will NOT start when its cold unless I spray starter fluid in the carburetor. Here is what I do to start it when its cold... I spray the stuff in both sides of the carburetor (Aisan carb) and quickly pump the accelerator about 5 times and it starts after about 2 tries with the starter fluid.

3 important things...

- I can take my foot off the accelerator within 10 to 15 seconds after starting with no sputtering or stalling.

- The vehicle runs great once started with lots of power, zero hesitation, surging, or stalling.

- After she's warmed up I can turn OFF the motor and leave for an hour or two and come back and she will start right up without starter fluid.

This is what I have done so far and it still requires starter fluid to start it cold...

- New spark plugs, spark plug wires, distributor cap, rotor, PCV.

- New battery (cleaned terminals and cables).

- New fuel filter and its two hoses.

- New fuel pump (mechanical).

- Seafoam treatment in carburator, crankcase, gas tank.

Some carb guy here wants $500 to rebuild this Aisan carburator and I really don't want to spend the bucks. Do you have any suggestions for what I should do next?

Thanks

Steve

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It sounds like a fuel/choke issue. There are a lot of articles on google concerning the carb. Should be a fairly cheap and simple fix, Kim. I have never rebuilt one of these but let me give some advice if you do. The specifications are not just suggestions. Set the specs exactly (in my experience this is a major source of problems with home rebuilds). Here is a good article on tracking down the cause. http://www.bluebassdesign.com/boonin/carb_faq/#cb

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I have the same carb. I bought the rebuild kit for about $25.00 at a local chain store. Unless your really good at this forget it. The are so many small parts I was pulling what few hairs I have left.

One thing this carb does have is an enrichment diafram for cold starts. It basically adds extra fuel when starting cold. It sounds like this may be your issue. My diafram was dry rotted. This piece does come in the kit and is mounted to the outside of the carb facing the front.

My opinion is these carbs are junk. I'm retrofitting a simple Rochester 1bbl. To my 1978 20R. My state is not anal on emissions with a vehicle so old.

I still have smaller left over parts from the carb. rebuild. I replaced what I could. JD and Waiter would probably have more specific information if this is not the problem. Good luck. Fred

OK I went back and checked my book. Its been over a year since my rebuild. The book identifies it as the auxiliary accelerator pump. It's vacuum operated and secured to the front of the carb body by 3 screws. Inside is the diaphragm and spring. I only found it was bad by accident. When I pulled the vacuum hose off raw fuel actually came out of the hose. I'm sure it has other functions beside cold starting. First check all your vacuum hoses to ensure they've good. Then try the kit and see what happens. If it works, it's a cheap fix.

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Remove the lid to the air filter (cold engine) depress the gas don't try to start it then go out and see if the choke plate is completely closed. It must be closed completely and have a bit of resistance to it. It maybe be nothing more then being gummed up little carb cleaner will fix that.. It is a complex carb with lots of tiny parts before I spent $500 I would look into a Holly or some other up grade if it comes down to that.

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I have an 82 5 speed Sunrader with the 22R with 60,000 original miles and it will NOT start when its cold unless I spray starter fluid in the carburetor. Here is what I do to start it when its cold... I spray the stuff in both sides of the carburetor (Aisan carb) and quickly pump the accelerator about 5 times and it starts after about 2 tries with the starter fluid.

Typical problem for an engine with a downdraft automotive carb. The accelerator pump is probably not working. It squirts raw gas into the carb whenever there is throttle-linkage movement. That's why a perfect running gas engine once cold will not start unitl you hit the gas pedal and pump it once or twice. When you do that it #1 squirts a charge of raw gas into the engine, and #2 closes the choke (unless you've got a manual choke). Unlike an engine with electronic fuel injection - you must manually inject a charge of raw gasoline into the engine's intake manifold for it to cold start. Atomized gas alone from the carb will condensde and stick to the inner walls of the intake when cold and never make it to the combustion chamber.

Some cars, tractors, and motorcycles with carbs but NO accelerator pump use other devices for flood the engine with gas for cold starting. Primer bulb, float tickler, etc.

Someone else mentioned the aux accelerator pump. That has nothing to do with starting. It is there to squirt raw fuel into the engine when the second stage opens up and there is a momentary time of too much air. In high performance carbs that setup is often called a "double pumper."

Look down the carb while moving throttle linkage. Any movement from idle speed up to half-way should make a squirt of gas like a water pistol would make. If not -get a $20 kit and fix the carb. The accel pump is not just for cold starting. It's for starting and for making up for a too-much-air lean situation that evolves anytime you try to accelerate.

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I have the same carb. I bought the rebuild kit for about $25.00 at a local chain store. Unless your really good at this forget it. The are so many small parts I was pulling what few hairs I have left.

One thing this carb does have is an enrichment diafram for cold starts. It basically adds extra fuel when starting cold. It sounds like this may be your issue. My diafram was dry rotted. This piece does come in the kit and is mounted to the outside of the carb facing the front.

My opinion is these carbs are junk. I'm retrofitting a simple Rochester 1bbl. To my 1978 20R. My state is not anal on emissions with a vehicle so old.

I still have smaller left over parts from the carb. rebuild. I replaced what I could. JD and Waiter would probably have more specific information if this is not the problem. Good luck. Fred

OK I went back and checked my book. Its been over a year since my rebuild. The book identifies it as the auxiliary accelerator pump. It's vacuum operated and secured to the front of the carb body by 3 screws. Inside is the diaphragm and spring. I only found it was bad by accident. When I pulled the vacuum hose off raw fuel actually came out of the hose. I'm sure it has other functions beside cold starting. First check all your vacuum hoses to ensure they've good. Then try the kit and see what happens. If it works, it's a cheap fix.

To each his own but I find any Rochester 1 or 2 barrel to be inferior to the Aisan carb on the Toyota. All carbs have small parts and all carbs get old as time goes by. The OEM Aisan carb is a one barrel in normal driving and becomes a two barrel when power is needed. A great setup. With a fixed one barrel or two barrel Rochester, Ball, or Holley - it cannot be two things. It is either too big for low power driving or too small for high power situations.

Since the OEM Toyota carb is both a one barrel and and a two barrel it works like this. Normal driving uses one barrel and one accelerator pump. When ever the throttle is moved to accelerate a squirt of raw gas is sent it to avoid a momentary lean situation. If you stomp on the pedal for high power - a vacuum assisted second stage (barrel) opens up and it has it's own aux. accelerator pump that again - sends in extra gas to avoid a momentary lean situation. Rochester did the same on a bigger scale with the Quadrajet four-barrel on big engines. Two small bores for normal driving and second large bores when high power was needed. But the Rochester was designed to open the 2nd bores very slowly since it had no 2nd accelerator pump. If they opened too fast the engine got lean and bogged down. That's why Holley "double pumpers" were often used to replace the Quadrajets.

The small Chevy and Ford four-cylinder cars like Chevettes, Vegas and Pintos first came out with 1 barrel carbs - often Holley or Rochester and they were bad on MPGs and power. Then later they got adaptable two-stage carbs like Toyota uses and got much better.

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JD.... The purpose of the AAP is to add extra fuel to the mix when the engine is cold. It's vacuum operated from the BVSV which senses the temp. of the coolant and applies vacuum if needed. It has NO EFFECT on a warm engine.

Maineah hit the first obvious thing to check. These carbs are tricky to rebuild. But if one piece from a $25.00 kit fixes the problem,its better than buying a new carb.

I chose the Rochester 1bbl. because it is very easy to work on. They used these carbs in Chevettes,Vega's and 6 cylinder trucks. Never heard of any problems with them. Eventually I'm adding a GM 1 wire alternator and a DUI distributor. My goal is to make my toy bulletproof. If I break down on the side of the road I know I should be able to fix it.

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JD.... The purpose of the AAP is to add extra fuel to the mix when the engine is cold. It's vacuum operated from the BVSV which senses the temp. of the coolant and applies vacuum if needed. It has NO EFFECT on a warm engine.

Maineah hit the first obvious thing to check. These carbs are tricky to rebuild. But if one piece from a $25.00 kit fixes the problem,its better than buying a new carb.

I chose the Rochester 1bbl. because it is very easy to work on. They used these carbs in Chevettes,Vega's and 6 cylinder trucks. Never heard of any problems with them. Eventually I'm adding a GM 1 wire alternator and a DUI distributor. My goal is to make my toy bulletproof. If I break down on the side of the road I know I should be able to fix it.

We might not be using the same terminology. In mechancial context - an accelerator pump is by defintion a pump only used when accelerating. An "aux" or "secondary" accel pump is used when accelerating and the aux stage of the carb opens up. Then there are 'cold start valves" (US terminology) to enrich the mixture when cold, and "power valves" to enrich the mixture when under full load. I have to look at my Jap manual and see what names they are using. If they are calling a cold enrichment valve and "accelerator pump" then they are using US technical language incorrectly.

With the one-barrel Rochesters, Autolites, Balls, Carters, etc. None were particularly trouble prone. Just crude and do offer the advantages of the Aisan carbs used on Toyotas (and later some GMs). Rochester is a very simple carb and has an accelerator pump that also goes bad. But you can change it without even takking the carb off the engine. Like I said though - it is a simple fixed CFM carb. Does not have two stages and cannot give the adaptable overall performance of a two-stage carb. The first Chevettes had one barrel Rochesters but then got improved to the two-stage two-barrel carbs and ran MUCH better. More power when needed and more MPGs overall. As I recall the two-stage carb that GM and Ford went to were Aisans and Webers.

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We might not be using the same terminology. In mechancial context - an accelerator pump is by defintion a pump only used when accelerating. An "aux" or "secondary" accel pump is used when accelerating and the aux stage of the carb opens up. Then there are 'cold start valves" (US terminology) to enrich the mixture when cold, and "power valves" to enrich the mixture when under full load. I have to look at my Jap manual and see what names they are using. If they are calling a cold enrichment valve and "accelerator pump" then they are using US technical language incorrectly.

With the one-barrel Rochesters, Autolites, Balls, Carters, etc. None were particularly trouble prone. Just crude and do offer the advantages of the Aisan carbs used on Toyotas (and later some GMs). Rochester is a very simple carb and has an accelerator pump that also goes bad. But you can change it without even takking the carb off the engine. Like I said though - it is a simple fixed CFM carb. Does not have two stages and cannot give the adaptable overall performance of a two-stage carb. The first Chevettes had one barrel Rochesters but then got improved to the two-stage two-barrel carbs and ran MUCH better. More power when needed and more MPGs overall. As I recall the two-stage carb that GM and Ford went to were Aisans and Webers.

This pump is specific to the asian 2bbl. carb Steve has on his toy. Its purpose is as I stated. I'm sure it means other things for different applications. The easiest check is to pull the vacuum hose off the unit. If there's raw fuel inside, the guts have to be replaced.

I owned 2 Chevettes (76&78) and 1 1981 truck. All used this carb and I never had any problem with performance or mpg. It's a personal choice for me.

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My Toyota carb book shows it but does not explain it. I found the explanation as written by the Japanese guy that invented it;

An auxiliary acceleration fuel feed device in an internal combustion engine used for a vehicle is disclosed. An auxiliary accelerator pump is provided for feeding an auxiliary acceleration fuel into the fuel supply passage of the engine in response to a decrease in the vacuum in the intake manifold. A vacuum control device in a vacuum conduit connecting the pump and the intake manifold is responsive to the engine temperature and the vehicle speed. The vacuum control device is arranged so as to close the vacuum conduit to prevent the supply of the fuel to the nozzle by the pump when the engine temperature and the vehicle speed is above respective predetermined levels.

Inventor: Takashi Kato
Original Assignee: Toyota Jidosha Kogyo Kabushiki Kaisha
Current U.S. Classification: 123/437; 261/34.2; 261/34.3
International Classification: F02M 706; F02M 108; F02D 1906

Obviously as the inventor describes it - it comes into use only when cold and only when accelerating. Not used during starting.

Here is more info from the inventors.

An acceleration pump delivers additional fuel to both the main intake passage and the auxiliary intake passage of an internal combustion engine, to facilitate cold starting. In such an engine, each main combustion chamber is in communication with an auxiliary combustion chamber, respectively. Coordinated means are provided for operating said acceleration pump and throttle valves in said intake passages. Communication between the acceleration pump and the main intake passage remains open at all times, but a passageway connecting the acceleration pump and the auxiliary intake passage is closed except when the ambient temperature is low. Closure of the connecting passageway is effected automatically or in coordination with operation of the choke valve for the main intake passage.

Inventors: Genjiro Hamakawa, Kenji Naito
Original Assignee: Honda Giken Kogyo Kabushiki Kaisha
Current U.S. Classification: 261/23.2; 123/179.15; 261/23.3; 261/34.3; 261/39.2; 261/DIG.74
International Classification: F02M 708

On the subject of Chevettes - I probably had every year and engine size ever offered including two diesels. The two-stage two-barrel carbs gave better MPGs and performance.

More info given to the US Patent office on the subject of the aux; accelerator pump.

1. An auxiliary acceleration fuel feed device in an internal combustion engine used for a vehicle, said engine having in a fuel supply passage, a carburetor having an acceleration pump for feeding an acceleration fuel into the fuel supply passage at the time of acceleration, comprising;

  • an auxiliary accelerator nozzle disposed in the intake passage,
  • an auxiliary accelerator pump in a fuel conduit connecting a supply of fuel with the auxiliary accelerator nozzle, the pump being operatively connected to the intake passage downstream of a throttle valve of the carburetor through a vacuum conduit so as to feed an auxiliary acceleration fuel to said nozzle in response to a decrease in the vacuum in the vacuum conduit, and,
  • a vacuum control device in the vacuum conduit responsive to the engine temperature and the vehicle speed and arranged so as to close the vacuum conduit to prevent the supply of the fuel to the nozzle by the pump when the engine temperature is above a predetermined level and the vehicle speed is above a predetermined level.

2. An auxiliary acceleration fuel feed device as recited in claim 1, wherein said auxiliary accelerator pump comprises a housing having a diaphragm therein, a vacuum chamber and a pumping chamber in the housing, which are separated by the diaphragm, said vacuum chamber being connected to the intake manifold downstream of the throttle valve via the vacuum conduit, a compression spring in the vacuum chamber arranged so as to bias the diaphragm, a first check valve disposed in the fuel conduit connecting the pumping chamber and the supply of fuel and allowing only inflow of the fuel to the pumping chamber from the supply of fuel, and a second check valve disposed in the fuel conduit connecting the pumping chamber and the nozzle and allowing only outflow of the fuel from the pumping chamber to the nozzle.

3. An auxiliary acceleration fuel feed device as recited in claim 1, wherein said vacuum control devices comprises a vehicle speed sensor, a temperature reactive switch and an electromagnetic valve in the vacuum conduit responsive to an electrical output from the vehicle speed sensor and the temperature reactive switch, the electromagnetic valve being arranged to close when the vehicle speed is above a predetermined level and the engine temperature is above a predetermined level.

4. An auxiliary acceleration fuel feed device as recited in claim 1, wherein said vacuum control device comprises a vehicle speed sensor, and an electromagnetic valve and an engine temperature reactive valve disposed in parallel in the vacuum conduit responsive to an electrical output from the vehicle speed sensor and responsive to change in temperature of the engine, respectively, the electromagnetic valve being arranged to close when the vehicle speed is above a predetermined level, the engine temperature reactive valve being arranged to close when the engine temperature is above a predetermined level.

5. An auxiliary acceleration fuel feed device as recited in claim 4, wherein said engine temperature reactive valve comprises a bimetal type temperature sensing valve

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I have an 82 5 speed Sunrader with the 22R with 60,000 original miles and it will NOT start when its cold unless I spray starter fluid in the carburetor.

To make a long carb-story short - if your "primary" accelerator pump was working your engine would start cold even without a choke; You'd just have to pump the gas pedal a lot. Each pump of pedal squirts a raw charge of liquied gasoline into the engine just like a water pistol would do.

If not working - even with the choke closed most engines will not start.

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Auxiliary Accelerator Pump Diaphragm (AAP)

The auxiliary accelerator pump diaphragm (AAP) is located at the front base of the driver's side of the carb. It has three screws and one vacuum line.

To check if it is bad, simply pull off the vacuum line and look and smell for fuel. If there is gas in the line, the diaphragm is punctured or cracked and should be replaced. I have heard of people simply plugging the vacuum port and being fine, although your idle/take off may stumble a little when cold.

All the AAP does is squirt a little extra fuel into the mixture when the engine is cold. It has no effect on the engine when warm - even when not working properly. The AAP is vacuum operated - when vacuum is applied the diaphragm opens which then adds a little extra fuel. The vacuum is applied by the BVSV which is screwed into a water jacket on the head. This senses the temperature of the coolant and applies or does not apply vacuum to the AAP.

A new diaphragm comes with any rebuild kit or can be purchased from the dealer and maybe from some aftermarket parts stores

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Auxiliary Accelerator Pump Diaphragm (AAP)

The auxiliary accelerator pump diaphragm (AAP) is located at the front base of the driver's side of the carb. It has three screws and one vacuum line.

To check if it is bad, simply pull off the vacuum line and look and smell for fuel. If there is gas in the line, the diaphragm is punctured or cracked and should be replaced. I have heard of people simply plugging the vacuum port and being fine, although your idle/take off may stumble a little when cold.

All the AAP does is squirt a little extra fuel into the mixture when the engine is cold. It has no effect on the engine when warm - even when not working properly. The AAP is vacuum operated - when vacuum is applied the diaphragm opens which then adds a little extra fuel. The vacuum is applied by the BVSV which is screwed into a water jacket on the head. This senses the temperature of the coolant and applies or does not apply vacuum to the AAP.

A new diaphragm comes with any rebuild kit or can be purchased from the dealer and maybe from some aftermarket parts stores

It squirts extra fuel into the engine's intake by vacuum operation when cold and the engine is running. Not when you're trying to start it. It's a kind of added system to the mechanical accel pump with vacuum and temp control instead of mechanical linkage. Same is often done with the ignition timing advance with mechanical and vacuum and temp controls.

The "primary" accelerator pump is what effects cold starting and when not working- it's near impossible to get an engine to start. When the aux is not working - it will not affect cold starting. Cold running - yes. Keeps the engine from bogging/hesitating when cold and you hit the gas. US carbs often just use one big one that is good for the cold and too big when warm.

Stevo - since you sent me a PM and asked - here is some more info. Accelerator pump failure is a common thing in any old carburetor. On some carbs you can put in a new pump without taking the carb apart. On others you cannot and usually with any - you have to buy the whole repair kit to get the new pump plunger.

I'll post some photos a few at a time. I tried to post all at once and the forum posting system seems to have crashed.

post-6578-0-90185800-1360343423_thumb.jp

post-6578-0-04995100-1360343427_thumb.jp

post-6578-0-47625600-1360343429_thumb.jp

post-6578-0-39210700-1360343432_thumb.jp

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I just want to clarify one of my posts. I was quoted someone else's previous post and the forum system seems to have had a "mini-stroke." So my writing got mixed in with what I was responding to.

This is what I was responding to and I am not the author . .

"Auxiliary Accelerator Pump Diaphragm (AAP)

The auxiliary accelerator pump diaphragm (AAP) is located at the front base of the driver's side of the carb. It has three screws and one vacuum line.

To check if it is bad, simply pull off the vacuum line and look and smell for fuel. If there is gas in the line, the diaphragm is punctured or cracked and should be replaced. I have heard of people simply plugging the vacuum port and being fine, although your idle/take off may stumble a little when cold.

All the AAP does is squirt a little extra fuel into the mixture when the engine is cold. It has no effect on the engine when warm - even when not working properly. The AAP is vacuum operated - when vacuum is applied the diaphragm opens which then adds a little extra fuel. The vacuum is applied by the BVSV which is screwed into a water jacket on the head. This senses the temperature of the coolant and applies or does not apply vacuum to the AAP.

A new diaphragm comes with any rebuild kit or can be purchased from the dealer and maybe from some aftermarket parts stores"

This is the part of the post that came from me . . .

It squirts extra fuel into the engine's intake by vacuum operation when cold and the engine is running. Not when you're trying to start it. It's a kind of added system to the mechanical accel pump with vacuum and temp control instead of mechanical linkage. Same is often done with the ignition timing advance with mechanical and vacuum and temp controls.

The "primary" accelerator pump is what effects cold starting and when not working- it's near impossible to get an engine to start. When the aux is not working - it will not affect cold starting. Cold running - yes. Keeps the engine from bogging/hesitating when cold and you hit the gas. US carbs often just use one big one that is good for the cold and too big when warm.

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Most carbs do not have aap's and it really is not needed the op said it runs fine once started does not stumble does not hesitate pretty much rules out acc pump issues if you want cold start fuel you have to have a working choke it pulls fuel from the main jets lots of it case in point a stuck choke will stall a running engine with too much fuel.

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Most carbs do not have aap's and it really is not needed the op said it runs fine once started does not stumble does not hesitate pretty much rules out acc pump issues if you want cold start fuel you have to have a working choke it pulls fuel from the main jets lots of it case in point a stuck choke will stall a running engine with too much fuel.

Good running does not negate the possibility of bad accelerator pump. All depends on the engine, timing advance, etc. The ability to accelerate smoothly is a balance between automatic timing advance and the accelerator pump. Such things are not always just "good" or "bad" either. If the acc pump linkage gets worn, or umbrella seal hardened, some accelerator pumps just get weak and pump enough for running and not enough for cold starting. Some engines don't even have an acc pump but those often have some sort of primer for cold starting. The argument in this case is kind of moot since in only takes a minute or so to look down the carb with a light, operate the throttle and see if it squirts gas or not. Also only takes a moment to check the choke. Also unlike most other carbed vehicles the Aisan carb has two accelerator pumps. One mechanical and one temp/vacuum controlled. That is usual. Aisan had a patent on it and I don't know if any other common carbs had anything similar. I did bench rebuilding of carb and I never came across one. Cold start and power valves yes - but not aux accelerator pumps.

The main point is (in my opinion) any engine with a working accelerator pump can be started with no choke at all. The pedal just has to be pumped a lot. On the other hand, many engines with perfectly working chokes cannot be started in extreme cold without a primer or the accelerator pump working. Back in the muscle car days I had countless cars with big carbs and no chokes at all. Just had to pump them a lot to cold start them. My British motorcycles never had chokes either. Just "ticklers" that held the float down and made the carbs flood.

At the slow 300 RPM cold cranking most engines cannot get enough velocity in the carb venturi sufficient to start the engine with the choke alone. Besides the velocity problem what little does get atomized sticks to cold metal in a long intake manifold and recondenses before it gets to the combustion chamber. That's why back in the days before fuel injection - when temps got below zero there were be dead cars and trucks all over the place. Not so common anymore. Now with EFI, most engines will start even at 100 RPM if they turn over once or twice - even at 20 below 0 F.

Even small engines e.g. on snowblowers that lack accelerator pumps have primers on top of the chokes for cold starting and they don't have long cold intake manifolds to travel through like on cars.

The cold-start system in a carb is just that . . . a system. You must hit the gas pedal at least once. That sends a charge of raw fuel into the engine not unlike what this guy was doing by spraying ether. The squirt of gas goes in, the choke gets mechanically triggered closed - you crank the engine and hopefully it fires. The second it fires the vacuum-operated choke-pull-off diaphragm and the throttle controlled unloader both open the choke up a crack - hopefully before the engine floods. Then as it warms - usually a bimetal spring and/or a electric heater help to open it all the way. The carb also has a mechanical choke-opener that works when you put the gas pedal all the way to floor.

Different engines behave in different ways and have their own quirks. I worked at several dealerships over in the past when all vehicles were carbed. Cold starting was a big issue in the northeast.

My 1985 carbed Toyota pickup with the 2.4 was one of the best starting autos in cold weather I've ever owned (before EFI). That tells me that Aisan carb had a good system. We had a morning when it was 32 F below 0 and cars and trucks were dead all over including my 65 Chevelle, 69 Dodge and either of my company service trucks - 1983 Ford Ranger. and an a 76 IH Scout. That Toyota with two batteries hooked to it barely turned over yet did start. It was so cold my gear shift knob got brittle and broke off and my vinyl seat covers cracked when I sat on them.

I'm basing what I am saying on observations working as a mechanic for 40 years and living in what I regard as a cold area. Your observations may differ and I cannot account for why (it's not my job). Whatever the reason - we are not going to agree.

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Lawn mowers, gas tractors large and small, stationary engines, chain saws,generators etc. all have no acc.pumps they don't need them they run at a constant speed they do however have chokes and start fine. Thank you for the carb lessons though I must say after 40+ years of being an auto shop owner, service manager and teaching for Bosch I will admit in 96 I did get out of the automotive field to work as the electrical/electronics supervisor for the Cumberland County P/D so I'm sure I have forgotten a good deal over the past several years.

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Lawn mowers, gas tractors large and small, stationary engines, chain saws,generators etc. all have no acc.pumps they don't need them they run at a constant speed they do however have chokes and start fine. Thank you for the carb lessons though I must say after 40+ years of being an auto shop owner, service manager and teaching for Bosch I will admit in 96 I did get out of the automotive field to work as the electrical/electronics supervisor for the Cumberland County P/D so I'm sure I have forgotten a good deal over the past several years.

Some gas engine farm tractors DO have accelerator pumps. I have two here. International Harvester with the British Zenith VNN downdraft carb. I also have a gas backhoe-loader with an accelerator pump in the carb.

In regard to small engines starting fine with chokes. Yes, and many made to be started in the cold also have fuel primers. Found in most snowblowers with float carburetors. It's also why many showblowers left in cold garages have electric starters to spin them over faster. Chainsaws (modern ones) have diaphram carbs not float carbs and many also have fuel primer besides the chokes.

One thing on this subject I forgot about. There are some people driving today that have never driven a carbed vehicle and not had to start it in the cold. It happened with my 30 year old daughter recently. She borrowed my 89 Suburu and could not get it started the next morning. Why? She had only driven fuel-injected vehicles and did not know you have to stomp on the gas pedal at least once to activate the choke and squirt some gas in the engine.

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Thanks everyone for looking this stuff up and providing photos, etc.

My head is kind of swimming but if I'm reading correctly there could be 3 possible issues: the choke, the accelerator pump, and/or a dried out diaphragm in the aux accelerator pump. Right?

BTW: the carb rebuild guy that wants $500 said on the phone that it sounded like the needle and seat valve to be replaced. Your thoughts?

I will check the vacuum hoses because in the photo below I see a couple hoses in the back right that aren't connected and I don't recall pulling those off the air filter housing. You are saying that when I pull the hose off the AAP that gas should NOT come pouring out of the hose? Does it matter if I buy the cheapest carb rebuild kit available?

I have the same carb. I bought the rebuild kit for about $25.00 at a local chain store. Unless your really good at this forget it. The are so many small parts I was pulling what few hairs I have left.

One thing this carb does have is an enrichment diafram for cold starts. It basically adds extra fuel when starting cold. It sounds like this may be your issue. My diafram was dry rotted. This piece does come in the kit and is mounted to the outside of the carb facing the front.

My opinion is these carbs are junk. I'm retrofitting a simple Rochester 1bbl. To my 1978 20R. My state is not anal on emissions with a vehicle so old.
I still have smaller left over parts from the carb. rebuild. I replaced what I could. JD and Waiter would probably have more specific information if this is not the problem. Good luck. Fred

OK I went back and checked my book. Its been over a year since my rebuild. The book identifies it as the auxiliary accelerator pump. It's vacuum operated and secured to the front of the carb body by 3 screws. Inside is the diaphragm and spring. I only found it was bad by accident. When I pulled the vacuum hose off raw fuel actually came out of the hose. I'm sure it has other functions beside cold starting. First check all your vacuum hoses to ensure they've good. Then try the kit and see what happens. If it works, it's a cheap fix.

I think the choke is working because the flap on the right does close when I try to start it. Another thing... stomping on the gas a few times before starting does raise the level of fuel in the sight glass.

Remove the lid to the air filter (cold engine) depress the gas don't try to start it then go out and see if the choke plate is completely closed. It must be closed completely and have a bit of resistance to it. It maybe be nothing more then being gummed up little carb cleaner will fix that.. It is a complex carb with lots of tiny parts before I spent $500 I would look into a Holly or some other up grade if it comes down to that.

JD, those carb photos you attached look different than my carb. Do you know if the stuff to rebuild the accelerator pump (not the aux accel pump) is included in a regular rebuild kit?

Typical problem for an engine with a downdraft automotive carb. The accelerator pump is probably not working. It squirts raw gas into the carb whenever there is throttle-linkage movement. That's why a perfect running gas engine once cold will not start unitl you hit the gas pedal and pump it once or twice. When you do that it #1 squirts a charge of raw gas into the engine, and #2 closes the choke (unless you've got a manual choke). Unlike an engine with electronic fuel injection - you must manually inject a charge of raw gasoline into the engine's intake manifold for it to cold start. Atomized gas alone from the carb will condensde and stick to the inner walls of the intake when cold and never make it to the combustion chamber.

Some cars, tractors, and motorcycles with carbs but NO accelerator pump use other devices for flood the engine with gas for cold starting. Primer bulb, float tickler, etc.

Someone else mentioned the aux accelerator pump. That has nothing to do with starting. It is there to squirt raw fuel into the engine when the second stage opens up and there is a momentary time of too much air. In high performance carbs that setup is often called a "double pumper."

Look down the carb while moving throttle linkage. Any movement from idle speed up to half-way should make a squirt of gas like a water pistol would make. If not -get a $20 kit and fix the carb. The accel pump is not just for cold starting. It's for starting and for making up for a too-much-air lean situation that evolves anytime you try to accelerate.

Is that the AAP in my photo below?

Auxiliary Accelerator Pump Diaphragm (AAP)

The auxiliary accelerator pump diaphragm (AAP) is located at the front base of the driver's side of the carb. It has three screws and one vacuum line.

To check if it is bad, simply pull off the vacuum line and look and smell for fuel. If there is gas in the line, the diaphragm is punctured or cracked and should be replaced. I have heard of people simply plugging the vacuum port and being fine, although your idle/take off may stumble a little when cold.

All the AAP does is squirt a little extra fuel into the mixture when the engine is cold. It has no effect on the engine when warm - even when not working properly. The AAP is vacuum operated - when vacuum is applied the diaphragm opens which then adds a little extra fuel. The vacuum is applied by the BVSV which is screwed into a water jacket on the head. This senses the temperature of the coolant and applies or does not apply vacuum to the AAP.

A new diaphragm comes with any rebuild kit or can be purchased from the dealer and maybe from some aftermarket parts stores

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Thanks but I don't think the problem is that simple. I wish it were though!

By the way everyone...

I forgot to mention this before but the seller told me that the Sunrader started fine when cold when he bought it 4 years ago but then his wife passed away and it sat parked in his driveway for as long as 4 months between startups.

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I just read it and it sounds like it could have been choke or accelerator pump issue which is what JD and someone else here said it could be. Too bad the guy that asked the question on justanswer didn't report what happened. Thank you.

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My head is kind of swimming but if I'm reading correctly there could be 3 possible issues: the choke, the accelerator pump, and/or a dried out diaphragm in the aux accelerator pump. Right?

BTW: the carb rebuild guy that wants $500 said on the phone that it sounded like the needle and seat valve to be replaced. Your thoughts?

The choke and the accelerator pump are possible causes of cold starting problems. The aux accelerator pump is not and has nothing to do with starting. It is there to allow the truck accelerate better when cold.

Any carb ":rebuild" entails a new "needle and seat." That's carb 101. it's a $10 part. Carb kits come in different degrees of parts-quantities. There are carb "gasket kits", carb minor rebuild" kits and carb "major rebuild" kits.

A "minor rebuild" kit will repair most carbs. Comes with all the gaskets, diaphrams, needle and seat, and acceleratlor pump plunger. For the Aisan in older Toyotas it can be bought for $10-$20. If a mechanic is slow and throrough it's a 3-4 hour job, start to finish. $20 in parts and 4 hours labor at $500 comes to $120 per hour. Sounds high to me. Is he giving you legal advice while he works on it for that money? Where I live, the highest rate shops are the new car dealers that charge $80 per hour. Small shops are usually $50. I'll add though that now-adays few "mechanics" know how to repair a carb. Many just yank them off and buy an exchange rebuilt and then add on their own "added value" fee. You could buy a rebult carb folr $325 and install it in an hour. Seems getting what you have fixed ought to be less, not more.

A "major carb" kit comes with a bigger harder parts. It is for a carb that has metal wear, bad float, etc. Rarely needed on small cars and trucks. Comes with new throttle shaft, float, shaft bushings, welsch/cup plugs, plus all the other stuff that comes in smaller kits.

The photos I posted of the carb are for a 1978. They change a bit as they get newer.

Note - large vacuum controls do NOT come in carb kits. They come separate. Your carb has a "choke pull off" control that does not come in the kit. If bad, you have to buy separate. It has nothing to do with cold starting. It is there to automatically pull your choke open once the engine is started. If bad - the engine runs overly rich after starting until it warms up. Once warmed up it does nothing.

One more comment. If you order a carb kit locally - like from NAPA it will be a $40-$60 price. Buy the same from a place like Rock Auto and get the same for $15.

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If that is a picture of your carb cold the choke is not closed. It needs to be closed all the way and have resistance when you try to push it open.

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...

I forgot to mention this before but the seller told me that the Sunrader started fine when cold when he bought it 4 years ago but then his wife passed away and it sat parked in his driveway for as long as 4 months between startups.

That is a common thing to happen although 4 months isn't very long. If a car or truck sits long enough without being run the carb dries out. The accelerator pump in your carb has an umbrella-type seal. When it gets dry and hard it stops sealing and stops working. Aisan and Rochester carbs are prone to that sort of thing due to the umbrella plunger-type seal. Webers and Holleys don't have them (they use diamphram-type accelerator pumps).

Also - mechanical linkage can freeze up when sitting too long. If it freezes your choke might not close when you stomp on the gas pedal to activate.

Sititng and drying out causes problems in all carb and also in fuel injection pump in diesels.

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Forget what I said about the Aisan carb having a plunger accel pump. The 2 barrel carb on the 2.2 does. But I got looking at the carb used on the 2.4 liter and it uses a diamphram pump similar to what Holley and Weber uses. So what I stated just confuses thing.

I also hadn't noticed you posted photos. Thanks to MaineAH for noticing. As he said - in the photo you posted the choke is wide-open. Hopefully that is a photo you took after it was warm?

If you choke is not closing, it could be a stuck-linkage issue or a broken bi-metal choke-spring coil.

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I think the vehicle was cold when I took that photo and because I have seen the flap on the left closed a lot I assumed that was the choke. Since you guys told me that isn't the choke (and after doing some reading online) I assume I will need to reassess this issue, right? In fact, I have never seen the flap on the left move at all. What should I do next?

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Simple tricks first.

Have somebody hold the gas petal to the floor and then squirt some WD-40 on the choke shaft and all the linkage. Wiggle it until it will close on its own.

If that doesn't work then you will have to start taking things apart. First thing to check is the coil spring in the round thing that the choke shaft goes into.

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You got 3 hands??? Gotta spray, wiggle and hold open at same time. Maybe a big rock on the pedal. The idea is to just hold the carb at WOT and not continually pump the accelerator pump, flooding the engine

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Yeah the lid at the top is the choke like WME said free it up good. It needs to close completely by it's self. Once you step on the gas it should snap closed ALL the way and when you push it with your finger it should fight you not rat trap tight but enough for you to feel it fighting you back. There are some gadgets that do other things to the choke but first things first make it move smoothly and close all the way and that probably will fix your start problem..

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What does "WOT" mean and won't holding the accelerator down flood the engine?

Wide open throttle.Once will not flood the engine pumping it will. All this should be done with the engine off of course.

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