Stall and no start on hot day; Fuel pump?

Discussion in '80-Series Tech' started by Brimley, Sep 14, 2018.

  1. Brimley

    Brimley

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    A couple of days ago, my 1993 FZJ 80 just stalled. It happened on a hot day, midafternoon, (hundred plus degrees) after driving around town for less than 20 or 30 minutes. It was otherwise running fine and has ran fine with routine maintenance for the last 10,000 miles over seven years. Temperatures under the hood were high because it was so hot out but it was running normal temperature about 192 ° or 193°. It was a clear and dry with no water splashing issue.


    Any insights are appreciated. Here is the particular history:


    It cranked over fine but did not catch begin to start at all. I didn't have time to check spark or fuel on the side of the road in my work clothes. I did make a wire jumper and check the code (OBDI) it flashed a "25" lean fuel cylinders. I also had a check engine light with the key on (normal).


    I had AAA tow at home while I went back to work. When I got home about two hours later it had cooled off considerably and would just start a bit for two or three seconds at very low RPM. I had stopped and got a new EFI relay and changed it just in case and it made no difference. A couple hours later it started and ran poorly particularly with acceleration as if starved for fuel.


    I got up the next morning when it was quite cool, around 80° and it had been sitting all night and it started and ran perfectly. I really don't want to drive it anywhere because I don't want to get stranded. I can't check whether it is a fuel or spark issue now as it's running perfectly.


    I have suspected the fuel pump first. Do they fail in a hot environment on an intermittent basis? I do not know howvold it is. I have never changed it.


    The fuel pump relay is my second suspicion. I would think that it fail all at once and if related once it cooled off and started working it would run fine, not first run poorly.


    I'm not sure what could be spark and perhaps relate to the hot day, maybe coil? Again given the lean fuel code (which hasn't returned) I suspect the fuel pump.


    Is there any way to check the fuel pump now that it is running fine? Maybe it is weak and susceptible to overheating?. I'm happy to put in a new pump etc. but I don't want to just start throwing parts at it. I will start by checking the fuel pump connections for corrosion etc. and pull the fuel pump relay and cleaning if I can,


    Any input is certainly welcome, particularly given the circumstances of failure.

    Thanks

    JCP
     
    Last edited: Sep 15, 2018
  2. Brimley

    Brimley

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    Top 'cuz you guys are smart.
     
  3. greentruck

    greentruck

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    Sounds like the vapor lock I'd get in my ol' FJ55. Very common and more so with heat and altitude, but never saw much of it being a problem with the 80 series, but I'm not familiar with the 3FE side of things.

    Did you happen to check for vacuum/pressure in the tank by cracking open the fuel cap?
     
  4. Brimley

    Brimley

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    Yes didn't seem to be much if any. Also It is a 93. (op was a typo)
     
    Last edited: Sep 15, 2018
  5. thatcabledude

    thatcabledude SILVER Star

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    What year is the truck? First post says “1990 fzj80”. I suspect that’s a probably a typo?

    Symptoms sound like it could be a faulty engine coolant temp sensor. Ecm could be getting readings that the engine is cold and dumping a lot of fuel as a result. Runs fine when it actually is cool, not so much when engine is up to full running temp.
     
  6. Brimley

    Brimley

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    Good catch. It's a 93.
     
  7. morganism

    morganism

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    60's and 80's both need a separate wire from the ignitor case to a solid ground, the bolts at the base of the cage get rusty, it gets hot, and you lose the ground. 100's added this wire as stock, to block and wheelwell.

    If the coil itself is not grounding, it will also cook the rotor in the distributor, check it soon.

    edit: if you keep your fuel tank at 1/4 tank and above, you will prob never need a fuel pump replacement.
     
  8. Brimley

    Brimley

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    Thank you. I'm sorry to say I don't know what or where the igniter is? Picture and/or description if you can:cheers:
     
  9. JLH911

    JLH911

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