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  1. #1
    Join Date
    Dec 2020
    Posts
    1

    Post Timing chain or carburetor?

    Hello all,

    I have a 1987 Supra Pirata with the PCM 454 in it with 1500 hours on it. The last time the boat was in the water (September 2020), it ran great and I had zero issues with it. That next weekend when I decided to put it back in the water to take it a spin, it would not start. It simply would click, so I put a new starter in it, new starter solenoid, new coil, new spark plugs, and a new battery in it. After that, it acted like it wanted to start but wouldn't. I noticed fuel dripping from the spark arrestor. I took it off and tried to start the boat and saw that the carburator was shooting fuel out of it and into the spark arrestor. I have tried putting fuel into the carb and trying to start it, only for it to shoot right back out at me. The fuel shoots about two feet out of the top of the carb when trying to start it. I then thought it may be a stuck float but I checked the floats and they don't appear to be stuck....the carb is a holley carb and was rebuilt about 5 years ago. The jets in the carb are also spraying fine, it just seems there's air being pushed back out which is causing the fuel to be sprayed. A friend of mine said it sounds like the timing chain. I'm just so confused because last time it was in the water it ran great, it didn't skip a beat. Any ideas how to check to see if the timing chain is the issue? Any ideas what else it could be? I was going to pull the carb on it and take it somewhere to see if it can be fixed but like I said, my buddy seems to think it's not the issue. Any and all help/advice is much appreciated.

  2. #2
    Join Date
    Jul 2007
    Location
    Flowery Branch Georgia
    Posts
    2,579

    Default

    The engine can jump the timing chain just by cranking if its loose enough. A compression test will tell you if the chain has jumped. You can also set the crankshaft at top dead center on number one cylinder and check the distributor to see if the rotor is pointing at number one .

  3. #3
    Join Date
    Jul 2007
    Location
    Flowery Branch Georgia
    Posts
    2,579

    Default

    Are you sure the new starter is spinning the correct way?

  4. #4

    Default

    Could an intake valve be stuck open causing air to be pumped back up though the carb on the compression and exhaust strokes?

  5. #5
    Join Date
    Jul 2007
    Location
    Flowery Branch Georgia
    Posts
    2,579

    Default

    Quote Originally Posted by Supra Bob View Post
    Could an intake valve be stuck open causing air to be pumped back up though the carb on the compression and exhaust strokes?
    Sure a compression test will tell you that and if the timing chain has jumped. This all started with the new starter ? Are you sure its right? Are you sure its spinning the correct way?

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