3FE Fuel Supply Problem - I FIXED IT! (1 Viewer)

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yooper

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Been fighting this for a while. :mad:

12/89 FJ62, all stock drivetrain (3FE)
Fuel pump failed last spring, replaced with OEM
Fuel pressure pulsation dampener failed in the fall, replaced (cleaned out intake at same time) with OEM

Ever since the dampener service, the truck has been acting weird on start up. The problem is intermittent, worst when the engine is "slightly" warm - when it's been sitting for several hours. When it sits overnight it always starts up fine in the morning with no problems.

Starts right up on the first few cranks almost every time, then slowly dies after two or three seconds of running. Rarely I can "save" it from dieing by feathering the gas pedal. After it dies it's hard to start, cranks and cranks, sometimes sputtering for a few seconds, and eventually just fires right up after multiple tries at cranking. The worst was yesterday when I cranked about 10 times for several seconds each with nothing, and then fired right up.

If it takes more than a few cranks to start up the first time (cold) then it doesn't die at all, whatever that means.

Once it's started it runs as smooth and strong as ever.

I've gone through almost the entire FSM fuel injection diagnostic at least twice and it all checks out ok. I don't have a pressure gauge to check fuel pressure, so I haven't done the pressure checks.

All vacuum hoses are fine - intact and attached.

I adjusted the TPS per the FSM.

This behavior is similar to when the fuel pump was going bad, only it only lasted a week and then just failed that time. This time it's been several months, sometimes with a few weeks with no problems.

The intermittent nature of it makes me suspect an electrical problem.

Any ideas? ???
 
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3FE Fuel Supply Problem

A SIMPLE STUPID ANSWER, BUT YOU DID CHANGE THE FUEL FILTER AND CHECK ALL HOSES AND FUEL LINES FOR TIGHT CONNECTIONS FREE FROM AIR GETTING IN?
 
3FE Fuel Supply Problem

A SIMPLE STUPID ANSWER, BUT YOU DID CHANGE THE FUEL FILTER AND CHECK ALL HOSES AND FUEL LINES FOR TIGHT CONNECTIONS FREE FROM AIR GETTING IN?

Yep, I changed the fuel filter shortly after the fuel pump replacement, and I flushed the lines with fuel, up to the fuel rail where the pulsation dampener connects. This is a high pressure fuel injected fuel system with an electric pump in the tank - if it has a leaky connection then fuel comes squirting out, not air in.

thanks for the suggestion, though.
 
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3FE Fuel Supply Problem

JUST A THOUGHT, I HAVE A 62 AS WELL BUT HAVE LUCKILY NOT HAD TO WORK ON THE FUEL SYSTEM YET.
 
3FE Fuel Supply Problem

sounds stupid but did the PO put another filter on it? happened to someone else here last spring. Is there a filter/sock on the intank fuel pump, drain/clean tank?
 
3FE Fuel Supply Problem

No PO involved in this problem. I replaced the fuel pump myself. Cleaned the tank. New filters all over. Flushed the fuel lines while the main filter was off just to get any chunks out - didn't see any and all lines flushed easily. No problems during the several months between the fuel pump install and the fuel pulsation dampener failure. My problem has been since I had the whole intake off and replaced the dampener, and the problem went away for a while and now is back. I suspect an electrical connection somewhere rather than the fuel pump/filter/lines/injectors themselves, but who knows.

thanks guys. Keep thinking!
 
3FE Fuel Supply Problem

Gotta love the 62

Check out the cold start injector and thermo switch for it. Might be haywire.

Do the pressure check

Also, check out the ICS and the PCV valve and hoseing. If the ICS is wierd it could cause this. Might be gummed up

Sounds to me that somthing is either opening or closing on or just after startup. I dont see fuel pressure is the issue. It would happen all the time.

Did you check out all the VSVs? One might be acting funny.

Gotta love the beast! :flipoff2:
 
I Fixed It!

I finally figured it out! :D :D

It was the fuel pressure regulator - it was failing closed, raising the fuel pressure, causing the fuel pump check valve to get stuck closed. It caused my first pump to "fail" (the check valve was permanently stuck closed but the pump itself was fine) and it caused my fuel pulsation dampener to blow and it caused my mpg to be horribly low (like 8 or 9 instead of the 12-16 or so I should get).

The truck would start ok cold because the lines and fuel cooled, fuel pressure went down, and the check valve opened. When the truck was warm the fuel pressure was still high - the truck would start at first with the fuel locked in the rail and lines, and then die when the pressure dropped because the check valve was stuck closed. Eventually it would open and she would start up and then run fine because fuel was flowing, keeping the valve open.

I replaced the fuel pressure regulator ($91.93 from cruiserdan - thanks Dan!) yesterday and all the problems went away, the truck is "seat of the pants" faster, quieter, idles smoother, and the exhaust no longer stinks!

I highly recommend a fuel pressure regulator replacement for any 3FE with funny fuel supply problems - rough idle, running rich, poor mpg, starting problems, etc. It's a ten minute install - literally three bolts.

Thanks for your help, guys! I am SO happy to be going into winter with a reliable vehicle.

:D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :cheers:
 
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Quick question. there has been talk of engine temp sens. and fuel guage rising at same point. mine has done this all too often. used to think it was just heat, but fuel gauge, ie pressure, rose too. did it do this to you too. mine runs rough in the same manner as yours did. some said it was the ground point of the two sensors, but they are clean and, i think, not at fault. i am soon to replace the fuel pressure regulator. my pump and dampner went out just like yours, so i know i have that same problem, but what about the engine temp/fuel guage prob. does this fix too.
 
Sean I thought you were the one always saying the fuel presure reg was a problem and it fixs all kinds of problem...........now to find you just now replaced it ;)

I really should do one on Connie's 62, I am sure it needs it.

stupid question(onlu cause I am to lazy to look) which thingy is the FPR?
 
Landpimp said:
Sean I thought you were the one always saying the fuel presure reg was a problem and it fixs all kinds of problem...........now to find you just now replaced it ;)

I really should do one on Connie's 62, I am sure it needs it.

stupid question(onlu cause I am to lazy to look) which thingy is the FPR?

John, look at the dates of the above posts. It was last fall - that is when I became the 3FE FPR Awareness Officer
 
LOL........................your right ;)

yooper said:
John, look at the dates of the above posts. It was last fall - that is when I became the 3FE FPR Awareness Officer
 
worked for me too. thanks yooper. But be careful when putting new unit on. first time I pinched the O-ring and spewed gas all over when I started it. After replacing the O-ring i tightened one bolt too tight and snapped the head off.:mad: Just fair warning
 
Sean I thought you were the one always saying the fuel presure reg was a problem and it fixs all kinds of problem...........now to find you just now replaced it ;)

I really should do one on Connie's 62, I am sure it needs it.

stupid question(onlu cause I am to lazy to look) which thingy is the FPR?

Landpimp, The FPR is the one on the driver side of the head, forward & towards the raditor. Kind of a poor discription but that should get you there.

John
 
Its this thing

0314071726.jpg
0314071726.jpg
 
Right on the front of the fuel rail. Very visible just looking at the front of the intake runners.
 
I thought this thread was deserving of a revival... my 89 62 has been plagued by the same problem since I bought it over a year ago! Fuel pump was replaced by previous owner, I had to replace the pulsation damper. I replaced the FPR 2 weeks ago and have not had a starting problem since!

As an added bonus my MPG jumped from 12ish to almost 15!

-Dustin
 
I was having EXACTLY the same starting problem as you were with my "new" '88 FJ62 (hard starting when hot). You've saved me WEEKS of frustration and probably a ton of money too. Got a new FPR from Toyota, put it on last night - BINGO. Starts every time all the time, more power, idles at the right RPM! Hope my MPG improves too... I wonder if I should just replace the dampener too - it's the original. Thank you, thank you, thank you, thank you...
 

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