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1986 Toyota 22RE EFI Dolphin

Another test drive from the boonies to the big city of ABQ today.  Humming along nicely at 55 - 60 there are intermittent sluggish moments of power loss.  It's not gradual.  It's like a big head wind hit us. Or someone gave our invisible Dolphin tail a yank to slow us down a second.  BAM! and then normal for a mile or two or three.  Not backfiring audibly.  Not driving in windy conditions and it happens when there are no semi trucks sucking the back tires.

Guess:  Even though the gas tank was replaced with a new one in Tucson ( a month ago ) there are still bits of stuff floating around that are swimming to the front of the line and blocking to create that power loss moment. 

Reason and Test:  Started on a half tank and seemed to get worse as the tank went down.  Have about 6-7 gallons left and will test by filling the tank to see if it's still happening in the morning.

Guess:  It has something to do with the codes 4&5 still flashing ( H20 heat sensor and 02 sensor respectively - both replaced but not with OEM Toyota parts.  New H20 sensor priced at $102 - cough cough cough).  I don't really think the hiccup in the drive and the sensors are connected.

Yeah, I'm tired of this problem too.

Any new thoughts or suggested tests I could try? Thanks in advance.

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:angry01:You are describing the classic symptoms of junk in the fuel tank. the junk floats near the surface of the fuel and as the fuel level gets lower it floats over the strainer gets sucked down and then poof, poof, cough. You don't want to know how to check for this problem.

Does your new tank have a drain in the bottom like the factory tank? Semi remote possibility, just a tank of bad gas from some where on the road. A slug of water will go to the bottom of the tank and sometime will drift past the strainer, poof, poof cough as engines don't run real good on water. May try a couple bottles of gas dry.

OMG now what?? Have you changed the fuel filter on the engine? Do you have anyone who can put a fuel pressure gauge in for you? A mechanical one stays outside duct taped to the hood, with an electrical one you can have the gauge inside. If the gauge drops and so does the engine, you know where to start. Other possibilities bad fuel pump, bad fuel pump wires.

Other things are really weird and I'll bring them up if all else fails.

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New Clues:  Mileage dropped precipitously from a bad 14 mpg to worse 9.5 mpg
Also there is still chugging with a full tank from Costco gasoline (so I'm thinking, not bad gas).  Will drive it again in a half hour after it sat and settled all night.
Also the new tank is 16 gallons.  The mechanic poured in a 5 gallon jug of gas in to get me started.  The needle was at the bottom line so I felt I could trust that when the needle hit the bottom line I still had 5 gallons.  Only this time that I filled up it was at the line and I filled it to 14.5 gallons.  The mechanic showed me the nasty rusty bits that he took out.  Expressed less than confidence in the float mechanism that drives the fuel gauge needle. 

Possibility:  He left the old nasty fuel gauge float in there and a piece of it has broken off, plugging up the fuel sending area and throwing off the reading?

History on fuel tank replacement - The mechanic was in a rush and sloppy.  Left vent hose drooping and useless, for instance.  Did a new fuel filter at the time (second one in a month/ 1200 miles), but his boss said to change this one out sooner than normal, which tells me that there was some part of the fuel delivery system that was not flushed and he knew it.

Is a fuel pressure gauge something I can get at a Napa or OReilly's? There's a spot on the dash free.  I was going to put a tach there but it may as well be fuel pressure. 

I'm in NM, so pretty arid.  Water in gas not likely unless from the pump that way.

Will check back this afternoon.

 

 

 

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Fuel pressure gauges are typically only installed temporarily for testing purposes. I don't think I've ever seen one permanently and if I did, I'd probably think the person was a bit OCD.

https://www.autozone.com/test-scan-and-specialty-tools/fuel-pressure-tester/innova-fuel-injector-pressure-tester/273356_0_0

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Bad fuel...not from rain in the camper fuel tank, but from the gas station tank. SOMETIMES the gas station fuel tank is very near empty and there is cr*p near the bottom of older tanksthat gets stirred up and sucked up by the tank pump. Most gas stations have a chunk filter but not a water separator. This why I asked if your new tank has a drain in the bottom. If It does get a qt jar and drain out some fuel and let it sit for a bit and see what in it. Clear gas or layers of stuff at the bottom.

Side note never buy fuel when you see the delivery truck at a station, talk about stirring things up.

Here are some cheap fuel pressure gauges, these are mechanical types so they get taped to the hood outside. There are for temporary use just to see if the fuel pressure matches the engine power surges.   http://www.jegs.com/c/Gauges-Tachs_Gauges/10339/10002/-1?N=1010339+4294953073+4294806370+29&Ns=P_PrimarySecondary|0||P_SalesVolume|1&Tab=SKU.

NAPA has some listed for $35, but may have to order them

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You MIGHT be able to rent a fuel pressure gauge test kit from Oreillys they have some tool they loan out.

Good fuel pressure on a 22RE is 38-40lbs at idle and a max of 44 going down the road. So a 15 lb gauge is useless.

ONE of the other possibilities I just remembered is a bad ignition igniter, their $$$$ so try everything else first.

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So the chugging (for lack of a better word) is worse now - bad enough that I am at the local Toyota dealer (groan).  Waiting to talk to a tech.  No drain on bottom of new tank that I could see.  Maybe there's something on one of the ends.  The way it's behaving - now no power - having trouble getting up any speed on hwy - makes me think we are onto the injectors again.  Running rich, that whole scene.  Which could be the EFI / TPS computer part of the situation. 

It would suck, to put it bluntly, to have to check and change out the injectors, fuel filter, and spark plugs for the third time since October.

 

 

 

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"Joe" suggested putting a couple of bottles of Tecktron or Lukas in to clean the injectors and bring one for the road.

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I put two bottles of techron into a full 16 gallon tank with gas loaded up at a time no tanker truck was nearby.

The Toyota tech informed me that here in ABQ the winter gas supply is generally lousy, but that he gets Costco gas too and does not think water in the fuel is an issue there.  Also that the altitude here is going to mess with my gas mileage.

So... we'll see...

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There are 10's of millions of vehicles out there right now using the very same fuel everyone else is, water in the fuel is less of a problem than it was years ago because of the ethanol content in the gasoline it is hygroscopic. Amazingly a gas engine will tolerate up to 5% water content. Altitude will affect your mileage. There is only one thing that is constant in your fuel injection system and that is fuel pressure everything else needs that benchmark as a reference you need to know what it is before you can blame any other part.

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In Tucson, a mere 6 weeks ago, the fuel pressure was measured as 30, resting at 35, by a real, honest-to-god mechanic.

What would make it change?

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One other thing the fuel system is under a lot of pressure opening lines while running is a very bad idea  the normal operating pressure is around 35 psi about 10# greater than your water system in the camper for an example.

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Who is opening lines while running? huh?

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32 minutes ago, Cynxing said:

In Tucson, a mere 6 weeks ago, the fuel pressure was measured as 30, resting at 35, by a real, honest-to-god mechanic.

What would make it change?

At the end of the fuel rail is a enrichment valve it is vacuum operated it allows the fuel pressure to raise under full throttle however if it fails it can affect the pressure but I wouldn't recommend replacing it just because, another fuel pressure check would verify if it has failed they don't fix themselves.

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30 minutes ago, Cynxing said:

Who is opening lines while running? huh?

You would be surprised, many times I have been told "it has plenty of fuel pressure" by those that opened lines. That of course actually told them nothing other than fuel was running out with no pressure check.

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What would make the vacuum operated enrichment valve fail?

 

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10 minutes ago, Cynxing said:

What would make the the vacuum operated enrichment valve fail?

 

They very rarely do. I think I have only seen one or two Toyota ones fail it would run poorly in general all the time.

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Then why are we talking about it?  And I asked what would make it fail, not how often.

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Perfect fuel pressure for a 22RE is 37-38 psi at idle with the vacuum hose hooked up. Remove the hose and it should jump to 44 psi. With out a FP gauge try starting the engine, warm it up and let it idle. Removing the vacuum hose and the idle should change...the efi is going rich, that means the regulator is probably working.

Matching fuel pressure to the surges is more important than the actual FP. 30psi ain't enough, but 35 psi is close enough. If the engine is surging  and the fuel pressure is stable then we need a different crystal ball.

Bad gas mileage USUALLY means its rich so pull a couple of spark plugs and see how they look. Soft black carbon means rich, hard white ash means lean. Lean is a whole another problem so we wont go there now.

With limited budget you need to be taking small exact steps toward solving the problem, taking big swings and jumping around or changing a bunch components at one time is expensive and may not fix the problem. So start with small and cheap 

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11 hours ago, Cynxing said:

Then why are we talking about it?  And I asked what would make it fail, not how often.

You asked what would make the pressure change. It's either that or a failed pump the latter would leave you stranded. There are two methods of fixing fuel injection systems, methodically or throw parts at it until it sticks your choice. Intermittent problems are the worst usually electrical not mechanical. Trial by fire is not the best way to start fixing injection systems a strong knowledge of how it all works is the most important and it probably would pay you to find an expert and say "fix it".

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Last year ,i have the same problem , intermittent hiccup. I change the  air flow meter. Inside it have the electrical contact for the fuel pump. I replace this parts at my local scrap yards

 

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2 hours ago, steeve said:

Last year ,i have the same problem , intermittent hiccup. I change the  air flow meter. Inside it have the electrical contact for the fuel pump. I replace this parts at my local scrap yards

 

Part of the diagnostics. Both the fuel pump switch and the resistance of the potentiometer just another thing in the checklist. If it runs chances are pretty high it's not the pump switch but it can be a resistor issue just one of several possibilities there is also a thyristor in there that senses air temp. No one said this would be easy. 

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