Help! Driving Across The Country. Need Advice!

[candace]

We're traveling across the country in a 1984 Toyota huntsman 4 cylinder carbureted with manual transmission. Yesterday after driving for about 3 hours, the truck started to shutter. I have an air to fuel meter which read 17 and above, corresponding with the shutter. We were able to stop the shutter by putting the truck in neutral. Although it would stop momentarily, the shutter would come back. Eventually it became so frequent, we had to pull over. Thinking that it might be a fuel delivery issue, we took the fuel hose off of the carburetor and turned on the fuel pump to see if there was blockage. However that was not the problem because we had a steady flow of fuel. Next, we opened up the carburetor to verify there were no problems there. No problem filling the bowl with fuel and no problem with the float moving up and down. I woke up this morning and started to drive again. No problems until about three hours in. Once again, the the shutter started. We have stopped several times for 30 min or more to let the engine cool. When we resume driving we can drive another 25 miles or so and the shutter starts again. Now we're thinking there may be a problem with the ignition coil or the pickup coil. We would love some help!

[rad wolfe]

Have you checked the fuel filter? it may be clogged up?

[linda s]

Is your whole vehicle shuttering? When that happened to me it was my brakes sticking. Old brake lines and a gunked up master cylinder, pressure wasn't releasing in the front brake lines. If I stopped for a while it would run free again but after driving and even a little braking it would bind up again. If you think it might be this bleeding all old fluid out of your brakes will help

Linda S

[zero]

I'm not sure what you mean by "shudder?" An audible vibration? Or more of a pulsation that corresponds with intermittant losses of power? And, it is for sure an "engine-when-running" or a "rolling" shudder? If you shut the engine off when coasting - does the "shudder" go away?

[Maineah]

Try this, if you have a spray bottle fill it with water start the engine and spray ign parts if there is a crack or a carbon trace it will start to run poorly or just quit when hit the right spot then replace the offending part. It does sound sort of ign related to me. Another thing you might try is disconnecting the vacuum line to the EGR and see what happens.

[Dolphinite no longer here]

What is "shuttering"?

[rad wolfe]

I thought they meant stuttering or sputtering, which is why I suggested the fuel filter .

[zero]

Where I come from in the auto mechanical world of the past 50 years - common connotation of "shudder" is a vibration, usually with some sort of steady rhythm. "Sputter" is when a vehicle hesitates when you hit the gas, perhaps spits back through carb, or has a cylinder misfire. Two totally different things where I come from. "Shudder" often from warped brake rotors, sticking brake caliper pistons from rust, bad universal joint in driveshaft, bad wheel bearing, bad driveshaft support bearing, etc. "Sputter from worn out accelerator pump in carb, plugged fuel filter, bad fuel pump, retarded ignition-timing, carbon-tracking inside distributor cap, etc.

Not exactly using scientific terms here. Need more info. All that counts in this context is what the original poster here means - and I don't know what that is.

[rad wolfe]

in fact the original post referred to a "shutter" not a "shudder" or "sputter" or "stutter" so who knows....only the OP.

[zero]

I just assumed the poster meant "shudder" not "shutter." Who the heck knows? The poster, I guess. Only "shutter" I am aware of that applies to an auto is the air-shutters used to block of air flow to the radiator in extreme cold weather (in big trucks and some very old cars). They were also used in warm weather in old cars to make them superheat to run the engines on kerosene instead of gasoline. No kerosene-burning Toyota trucks around that I know of. My 1936 John Deere will burn it though (it has shutters).

[5Toyota]

no body mentioned vaper lock but who knows need more info.

[snail powered]

The word shudder sounds very much like the word shutter. This kind of spelling error is quite common if you normally hear something in conversation but rarely read that word in context. Most especially so in certain areas of the country were many of the consonant sounds are pronounced with a softer accent on them.

[linda s]

Candace I see you checked in at 1 in the morning but didn't post anymore info. Doesn't matter what you meant on your original post We can't help unless we get more info. Explain it more clearly or tell us what you've found so far and we will help if possible. Where you are is good too. Might be one of us near who is willing to look at it. Never know, good things do happen

Linda S

[snail powered]

Article about what situations could be causing the shuddering which is likely misfiring.

http://www.autotap.com/techlibrary/diagnosing_misfires.asp

[candace]

Thanks everyone for your help. I will try to explain the "shudder". It's a lurching movement. It feels like the truck will die if I don't take my foot off the gas. Like the engine is trying really hard and on the verge of quitting. This is coming from the front of the truck, under the hood. We stopped for about an hour, close to the border of Colorado in Kansas. As the sun went down and the temperature cooled, we took off again, driving three more hours to arrive in Denver without experiencing the problem again. Still unsure of the next step to take in diagnosing the problem. We want to head to the Tetons in Wyoming, but would like to get this fixed before we do.

[candace]

I'm not sure what you mean by "shudder?" An audible vibration? Or more of a pulsation that corresponds with intermittant losses of power? And, it is for sure an "engine-when-running" or a "rolling" shudder? If you shut the engine off when coasting - does the "shudder" go away?

Thank you! you have given us the vocabulary we needed to describe what's happening. It is more of a pulsation that corresponds with intermittent loss of power. It is definitely only happening when we are in gear pushing the accelerator. In neutral, it stops happening and coasts smoothly.

[zero]

How hot is it (air temps, that is)? "5Toyota" mentioned in his post the possibility of vapor-lock. It is almost unheard of nowadays since just about all cars and trucks have electric fuel pumps. It can only happen with a mechanical pump. But - I'm thinking maybe your Toyota has one? My 1978 Toyota Chinook and my 1988 Toyota Minicruiser both have electric pumps but I'm thinking the mid-80s 22R engines with carbs have mechanical pumps. If yours DOES have one - then vapor lock certainly is possible. That's the sort of thing that can come and go. Gets the worse when driving in extreme heat. A plugged filter won't be intermittent. It can certainly make the engine buck when hitting the pedal - but it will do so consistently. Not on and off, like you are experiencing. Intermittent problems can be very difficult to diagnose (as I guess you know). Electronic problems (ignition) can also be intermittent but usually not "good for three hours", then "not" like you describe. Usually if an electric module or coil is going bad - it gets hot and craps out.Then cools off again and works - until it gets hot and craps out again. If you decide vapor lock IS your problem - best way to eliminate it is to install a low-pressure booster electric pump as close to the fuel tank a possible. You hook it in series along with your mechanical pump. If I was around home and trying to diagnose a problem like this - I'd just take a 5 gallon boat gas tank, laying it on the hood and let it gravity feed gas to the engine. If it then ran fine - I'd know it was a fuel starvation problem. I realize such a test is not really feasible while on the road traveling.

[Skydancer2992]

As a temporary measure:

Driving with a full tank will help with vapor lock by providing more head pressure at the inlet of the pump.

If you are not going too fast, you can drive with the hood cracked open at the safety catch.

I did the above steps in college when I owned an old 1976 AUdi Fox.

[candace]

Thanks for the replies. The truck does have an electric fuel pump. So, I guess it's not vapor lock. The air temperature in the middle of the day was about 90 degrees. When we started driving again in the evening, the temp had dropped quite a bit. Probably in the low 70's.

Edited August 16, 2015 by candace

[fred heath]

I'm thinking contaminated fuel. Did this problem start happening after a refueling stop?

I've seen cases where contaminates lay in the fuel bowl only to suddenly float up and block the jet(s).

Try running some "Lucas" gas treatment and see if this helps. Just pour into your gas tank.

Change the fuel filter at the same time.

[5Toyota]

I had vaper lock happen once with a 77 20 R with an electric in tank fuel pump did not stall . but had to stop and wait for it to cool the fender mounted clear gas filter was foaming and boiling was at hi altitude in Colorado.

[candace]

How hot is it (air temps, that is)? "5Toyota" mentioned in his post the possibility of vapor-lock. It is almost unheard of nowadays since just about all cars and trucks have electric fuel pumps. It can only happen with a mechanical pump. But - I'm thinking maybe your Toyota has one? My 1978 Toyota Chinook and my 1988 Toyota Minicruiser both have electric pumps but I'm thinking the mid-80s 22R engines with carbs have mechanical pumps. If yours DOES have one - then vapor lock certainly is possible. That's the sort of thing that can come and go. Gets the worse when driving in extreme heat. A plugged filter won't be intermittent. It can certainly make the engine buck when hitting the pedal - but it will do so consistently. Not on and off, like you are experiencing. Intermittent problems can be very difficult to diagnose (as I guess you know). Electronic problems (ignition) can also be intermittent but usually not "good for three hours", then "not" like you describe. Usually if an electric module or coil is going bad - it gets hot and craps out.Then cools off again and works - until it gets hot and craps out again. If you decide vapor lock IS your problem - best way to eliminate it is to install a low-pressure booster electric pump as close to the fuel tank a possible. You hook it in series along with your mechanical pump. If I was around home and trying to diagnose a problem like this - I'd just take a 5 gallon boat gas tank, laying it on the hood and let it gravity feed gas to the engine. If it then ran fine - I'd know it was a fuel starvation problem. I realize such a test is not really feasible while on the road traveling.

Update: I think it could be vapor lock. Although the truck has an electric fuel pump, it was added by the previous owner. The location of the fuel pump is under the hood, close to the engine, where it can become very hot. Vapor lock seems the most likely diagnosis as the problem happens after driving for several hours and in hot outside temperatures. Someone suggested that I wrap the incoming lines with cork tape. Going to try that.

[zero]

Update: I think it could be vapor lock. Although the truck has an electric fuel pump, it was added by the previous owner. The location of the fuel pump is under the hood, close to the engine, where it can become very hot. Vapor lock seems the most likely diagnosis as the problem happens after driving for several hours and in hot outside temperatures. Someone suggested that I wrap the incoming lines with cork tape. Going to try that.

Vapor lock is near impossible when the pump is at the fuel tank. The "lock" occurs on the suction end of the pump and the liquid becomes vapor. An electric pump should never be mounted in front for any reason. Most are designed only to push fuel and have very little suction capability. Mount the pump as close as possible to the fuel tank - or just get rid of it IF your engine has a mechanical pump. Mechanical pumps ARE designed to suck fuel, unlike most electrics. Note - there are exceptions and a few expensive diaphragm-type fuel pumps CAN suck fuel. I doubt that is what you have. The electric pumps you're going to see in an auto-parts store are pulse or rotary and neither can work properly mounted under the hood.

[zero]

The fuel pump in this photo is one of the few that would work mounted under the hood. It's expensive and not commonly seen in autos. I have one in my diesel truck. A $25-35 pulse or rotary electric pump like commonly sold in auto-parts stores will not work.

[5Toyota]

as far as I know all 22R carb engines came with a mechanical fuel pump mounted on the left side of the head . wonder why he would of put on an electric pump. if it was me I might see about putting a mechanical pump back on it . with the valve cover off the cam that operates the mechanical pump can be easly seen. unless there was a problem with the cam lobe why change to that. Toyota changed the later 20R about 79 or 1980 to a mechanical pump .

[jjrbus]

This is a question for my esteemed colleague's here, not an answer. If it is vapor lock would it be possible to pour water or apply wet cloths to fuel pump and lines to cool them off when it happens? If this worked a couple times it might confirm the vapor lock diagnosis? Jim

[zero]

This is a question for my esteemed colleague's here, not an answer. If it is vapor lock would it be possible to pour water or apply wet cloths to fuel pump and lines to cool them off when it happens? If this worked a couple times it might confirm the vapor lock diagnosis? Jim

With conventional "vapor lock", yes. But when someone has issues with an electric fuel pump mounted under the hood - there can be fuel delivery problems with no vapor lock (not the sort we're talking about anyway). Same sort of principle why you can't pump water out of the ground that is deeper then 27-29 feet with a pump above ground (like a pitcher pump). The weight of the water at that depth demands so much vacuum to pull it against gravity - that it heats up and boils at room temperature. Once a vapor, the pump cannot suck it up.

[candace]

Here is the pump our truck has: http://www.amazon.com/Airtex-E8016S-Electric-Fuel-Pump/dp/B000C1LW0E/ref=sr_1_2?s=automotive&ie=UTF8&qid=1439857341&sr=1-2&keywords=Airtex+E8251

I bought this one today in case I need to replace it.

http://shop.advanceautoparts.com/p/holley-mighty-might-electric-fuel-pump-12-427/10717109-P

Edited August 18, 2015 by candace

[linda s]

Am I missing something? Neither of these pumps seem to come up as the right part for a 1984 Toyota pickup. Both also have way lower pressure than the stock mechanical pump.

Linda S

[candace]

Am I missing something? Neither of these pumps seem to come up as the right part for a 1984 Toyota pickup. Both also have way lower pressure than the stock mechanical pump.

Linda S

The previous owner added a Weber carburetor which requires a low pressure pump.

[WME]

The Holley is a bit to much pressure for WEBER carb. Max pressure should be 3.5 psi. MORE important the pumps should be mounted with in 12" of the fuel tank so that they can push the fuel. Holley makes a good regulator 12-804 factory setting is 2.7 lbs and it is adjustable from 1-4 lbs

[5Toyota]

I have had two weber carbs one on a datson and one on a 20 R Toyota motorhome datson had a mechanical pump 1978 Toyota had the stock in the tank electric pump and never had a problem. and yes you should be able to use a stock mechanical pump. if you need to adjust the fuel pressure you can get an adjustable in line fuel pressure regulator and put it on the gas line ahead of the carb. I have never used one but I have seen them.

[zero]

Here is the pump our truck has: http://www.amazon.com/Airtex-E8016S-Electric-Fuel-Pump/dp/B000C1LW0E/ref=sr_1_2?s=automotive&ie=UTF8&qid=1439857341&sr=1-2&keywords=Airtex+E8251

I bought this one today in case I need to replace it.

http://shop.advanceautoparts.com/p/holley-mighty-might-electric-fuel-pump-12-427/10717109-P

That electric pump is not designed to work under the hood and it won't (not correctly, anyway). The Walbro FRB electric pump I posted will. So will a mechanical pump. The electric pump you posted needs to mounted in back close to the fuel tank and as low as possible. And low pressure has little to do with anything here. Virtually all automotive carbs can run fine with NO pressure. Just flow is needed. That's why vehicles with gas tanks mounted high enough to gravity feed have no fuel pumps. High pressure is the problem with carbs. 6 PSI is usually the most a carb with a float can handle, and 2- 4 PSI max is preferred. A mechanical fuel pump and the electric pump you posted both meet those requirements. The problem is with the pump being mounted too far from the tank and higher then the tank. Those el-cheapo electric pumps are not designed to do that.

[zero]

By the way, when I said the pump you posted was fine as far as pressure goes, my reference was for the one you have under the hood (the Airtex). NOT the new Holley you just bought. That is not considered a "low pressure" pump and I would not use it. That is a "medium" pressure pump. That Airtex is rated 2-4 PSI which is good for small engines on lawn mowers and garden-tractors and also small car engines that have carbs with small floats, needle & seats for fuel control. That Holley is rated 4-6 PSI and designed for bigger auto engines with bigger floats, needle & seats. That Holley is also NOT suitable to mount under the hood. It makes too much pressure and is not designed to draw fuel from a distance and height. It's bad enough when the RV is on a flat road. When going up a steep hill - it gets real bad since the tank gets way below the engine compartment (where the pump is mounted now). The old Ford Model T trucks had no fuel pump with the gas tank in back and mounted a little higher then the engine. Worked fine until you came to a steep hill. Then the engine would starve for fuel unless you turned around and backed up so the gas tank stayed higher then the engine. Not quite the same issue as with your Toyota, but you get the idea. If you really want an electric pump - why not just buy a pump that is rugged and made for the job. That's the Walbro FRB I posted. It's one of the few on the market that is very durable and can draw fuel from a distance. Even so, even if I had that one, I'd still have it mounted by the tank. If I had your rig, I'd just put a new mechanical pump on the engine and call it "good."

[zero]

Here are some pumps that are low pressure (4.5 PSI max) and are suited for your Toyota. None or suited to be under the hood except the mechanical pump or the two Walbro reciprocating pumps that are very pricey. You cannot go by what some auto parts stores listings show as adequate. Many are incorrect. Especially from NAPA.