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40 runs like crap sometimes

Discussion in '40- & 55-Series Tech' started by MJM, Jul 5, 2005.

  1. MJM

    MJM SILVER Star

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    ? for some of you it is a 1980 FJ40 carb was rebuilt 2 years ago by Jim C. the problem is occurrs after the truck has driven awhile and then parked for 5-6 hours it starts but will not idle and will stall if the gas is not applied. It seems to happen more at night than during the heat of the day. The truck is all smogg but no carb cooling fan is present, snorkle. I am lost with this one I have replaced fuel filter wires, plugs and other normal bits am I missing something?
     
  2. Pin_Head

    Pin_Head

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    5-6 hours is long enough for it to cool down, so it is not a hot restart problem. Does your choke work and if so, does it help with the restart? What is the fuel level in the bowl after it cools down and after you start it? W/O the carb cooling fan, fuel tends to boil out of the carb when you shut it off.

    More information would help.
     
  3. FJ40Jim

    FJ40Jim The Cruiser Whisperer SILVER Star

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    Sounds like the fuel system is cooking off. Get the carb cooling fan operable and see if that takes care of it.
     
  4. MJM

    MJM SILVER Star

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    I do not think it is the carb cooling fan

    The reason I say that is b/c the fan never worked over the past 5 years and the problem is just now happening. THe choke does work but does not help it during the restart and once it gets going the only thing that will keep it running is a heavy foot. The problem happens most when lets say I park the truck at noon and go to restart at night many many hours later so I am sure the truck is cool. Could the gas be boiling off? Why will start just fine the next day?
    Thanks
    MJM
     
  5. Pin_Head

    Pin_Head

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    Sure it could be boiling off. Maybe your manifold is running hotter than it used to. Make sure that the ingition is not retarded. Check the fuel level in the carb before starting it. If may be hard to start because it has dumped all the fuel in the manifold and it is flooded. After sitting overnight, it has had time to drain into the engine or evaporate.

    Try the flooded engine start routine:

    Choke open all the way.
    Floor the gas pedal and hold it down (don't pump it).
    Hit the starter key and hold the pedal down until it catches and runs, then let the pedal up.

    If it starts much easier with the throttle wide open, it is flooded. The carb could also be siphoning fuel out of the idle and/or transition ports. All of the air vents in the fuel circuit would need to be plugged for this to happen, but it having the buel constantly boil out promotes this.
     
  6. FJ40Jim

    FJ40Jim The Cruiser Whisperer SILVER Star

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    The truck may be cool after 5 hours, but the fuel has boiled out of the carb and lines. The fan is there for a reason: Toyota recognized the smogged trucks were having serious heat soak issues. The fan is broken, truck has starting issues. Fix fan, continue diagnosis.

    Here's an interesting question: why did a smogged 1980 start easily w/ no carb fan? Was the heat riser inop? Bad cat? wrong T-stat? Stuck fan clutch?
     
  7. bonzai

    bonzai

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    Allways start simple/cheap-crazy