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Thread: Marine carb just rebuilt, now I can't get up to full RPMs.

  1. #1

    Default Marine carb just rebuilt, now I can't get up to full RPMs.

    I just rebuilt my 2300 because my boat was running a little rich, but other than that, it was running fine and reaching 4600 RPMs. Since I rebuilt the carb, it idles great and isn't fouling plugs. However, the boat is not accelerating well, and is only reaching 3200 RPMs at full throttle. It's now also backfiring through the carb on occasion at full throttle. I've never had that issue before. I'm running the air screws 1 turn out from lightly seated. A 2.5 power valve, and 68 & 67 jets. The jets were in the carb before the rebuild. The distributor cap has also recently been changed. The accelerator pump has been adjusted to Holleys specs. The engine it's on is a 3.0L Volvo Penta GS.

    The choke is opening up fine and I don't know where to start troubleshooting this issue. Any help would be appreciated.

  2. #2


    Sounds like it's running out of gas. Float level too low?
    Also test fuel PSI. Idle PSI and wide open throttle should be about the same. -1 PSI at the most.

  3. #3


    The float was set parallel to the bottom of the bowl when inverted, as instructed in the rebuild kit. What should I test PSI on?

  4. #4


    6-7 psi...

  5. #5


    Wisky Badger,
    Can you tell me if this is the same model as the GLP-J 3 liter? Reason I'm asking, is that I had the Demon 2bbl (?CFM) on the engine, and just couldn't get it to run right. Eventually, I'm going for a replacement, and Holley tells me I should replace it with a CFM 300 CFM (of which I've ordered). I see yours is running a 500 cfm. Just wondered if you could shed some light on this for me?


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