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Jlg 40H issues

Discussion in 'Other Construction/Demolition Equipment' started by rbcanaday, Mar 20, 2022.

  1. rbcanaday

    rbcanaday Well-Known Member

    Joined:
    Mar 11, 2015
    Messages:
    69
    Location:
    Walterboro, SC
    Have a Jlg 40h with ford 423 motor. Rebuilt carb but still doesn’t seem to idle just right. Will fire right up 9 out of 10 times but every so often it won’t crank for anything. Takes numerous starts to get an attemp to fore them runs crappy for 2-3 mins before leveling out.
    Carb rebuilt, new fuel pump, new fuel shutoff solenoid. I have a clear inline filter just after gas tank. Filter never fills with fuel. Not sure why. Could that mean carb isn’t getting enough fuel?
    also machine doesn’t want to shut down unless I kill master switch. It wants to diesel if shut off normal way. I replaced fuel shutoff but it’s still doing it.

    Any thoughts or advice?
     
  2. OFF

    OFF Senior Member

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    Occupation:
    HD Mechanic
    Location:
    Alberta, Canada
    Those clear plastic fuel filters very often don't seem to fill up. The engine doesn't care, they run anyway.

    Dieseling on a gasoline engine is a function of idle speed. Have you maybe got the idle speed set using the screw on the throttle plate rather than letting the governor do it? Does the power to the fuel shutoff stop when you turn off the ignition ?
     
  3. rbcanaday

    rbcanaday Well-Known Member

    Joined:
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    69
    Location:
    Walterboro, SC
    Maybe you are right about that clear filter. It seems to run ok for most part.
    The idle screw could be set wrong. I had a mechanic help me rebuild and setup the carb. He is top notch mechanic but he could have it adjusted wrong. I’m gonna hook a light to the fuel shut off and make sure it does loose power. Will update soon.
     
    OFF likes this.
  4. rbcanaday

    rbcanaday Well-Known Member

    Joined:
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    Messages:
    69
    Location:
    Walterboro, SC
    Little help needed. Having same issues. Couple cylinders started leaking. Machine sat for 2 months while fixing his cylinders. Now it won’t badly run. Idle at best when loaded it shuts off.
    So I’ve tried to swap to LP. Those was leaking and nasty so I temporarily rigged up another hose. Machine cranks and idles great but again when loaded heavy it shuts off. it’s like it can’t get enough fuel or floods.
    I bypassed the relief valve when I rigged hose. I notice one fitting has a spring and maybe some type office in it. Could that be the issue? Do I possibly need to rebuild the lp regulator. I’ve got new hose made so I’ll try it soon.
    I was hoping to avoid the 700-800 new carb. Any ideas would help.
     
  5. OFF

    OFF Senior Member

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    One thing about propane, the "window" of fuel mixture is actually very narrow. Too little propane, it won't ignite. Too much propane won't ignite either. Bypassing relief valves probably won't work for you. Google says the flammability range is from 2% to 10 percent. Not much wiggle room.
    Strange though that both fuel systems are acting the same way. A weak ignition will crap out as soon as the engine is under load and cylinder pressure rises to a point a weak spark will no longer jump the gap.
     
  6. rbcanaday

    rbcanaday Well-Known Member

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    Location:
    Walterboro, SC
    Off- I would say both girls act the same. On gasoline it will barely run period.
    ON Lp is idle great and and I can manually move the throttle and it will rev way up and hold. Will rev to the point that I back off because I think she’s turning too many rpm’s. But when I load hydraulics the motors doesn’t rev high enough and stalls. Usually shutting off.
     
  7. rbcanaday

    rbcanaday Well-Known Member

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    Location:
    Walterboro, SC
    So do you suggest new plugs and wires maybe?
     
  8. OFF

    OFF Senior Member

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    Occupation:
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    sounds like maybe the governor is messed up?

    You make it through the hurricane ok?