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Thread: 850 carb pop on hot start only.

  1. #11


    Still doing the same thing, but maybe I described it wrong. It doesn't really backfire or pop, but tries to start instantly, but doesn't. Only happens when engine has sat more than 10 minutes HOT. If you shut it down HOT and restart immediately, no problems. Have adjusted idle mixture screws, floats, fuel pressure regulator, timing (16° initial & 34° total, changed plugs, tried with and without vacuum advance, checked for fuel dripping from booster after shutdown, it isn't, no black smoke on startup after hard start problem, plug wires are MSD 8MM new, new BPE 60K volt HEI distributor, fuel lines, Carb and fuel pressure always cool enough to touch, so they aren't getting too HOT. Is something creating a HOT spot in the cylinders that's why it tries to fire off immediately only to end up with a hard start when I'm having that problem? If I pump the pedal it becomes very hard to start, if I just continue cranking without hitting the pedal it will start. Also, stated earlier truck runs 200°F while cruising, that was incorrect, no matter how hot outside never goes above 180°F in cruise or idle. I'm completely stumped by this.

  2. #12
    Join Date
    Jan 2010
    Brisbane, Australia


    Quote Originally Posted by 496C10 View Post
    If I pump the pedal it becomes very hard to start, if I just continue cranking without hitting the pedal it will start.
    I'd say the engine is partly flooded after the 10+ minute heat soak. Try opening the pedal only the minimal amount on the next test. What air cleaner are you using; is it fed with cold air? Gary
    Regards, Gary

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