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  1. #1

    Question What's with the engine?

    Here's what's happening:

    Cruising along ......doesn't seem to matter what speed or rpms.... everything is peachy...

    engine slows can hear it....rpms & speed drop
    engine picks back up and is fine again

    engine slows down.....

    engine picks back up...

    this happens over & over... from anywhere from 30 seconds to 5 minutes or so

    then it stops doing it all on it's own and acts like it never happened in the first place

    If it was a car it would sound like a low rev....count to three or 4...then foot off the accelerator...then low rev...count...then foot off...repeat until insane

    99 Merc 5.7 about 120 hours on it

    all normal maintenence is done on an ongoing basis

    Got a once over last month while it was getting the new ignition installed last month. The wrenchers didn't see anything else that needed to be done.

    Possibilities? Ideas? Guesses?

  2. #2
    Charter Member #927 Charter Member Payton's Avatar
    My Boats:
    1991 34' Super Hawaii
    Join Date
    Jan 2001
    Fuel filter?

  3. #3
    Charter Member #1171 Charter Member obnoxus's Avatar
    My Boats:
    Join Date
    Feb 2001
    New Lenox , Il
    does it idle smooth? If idle surges also, it is probably a bad ECM. if thats ok I would put a fuel pressure guarge on it you could see while it was acting up.

  4. #4
    He pulled the filter and said there was stuff that didn't look like "gas" stuff on it.......... he rinsed it in gas and we'll see how that does today...

    He said it idles smooth the whole time and if getting a new fuel filter tomorrow doesn't fix it we'll grab a gauge to check it while we're in the water.

    Wer'e up for any ideas and will check anything that anybody can come up with to figure this puppy out

  5. #5
    Registered car54driver's Avatar
    Join Date
    Mar 2001
    Russell Springs KY
    A friend of mine had a similar situation. They ended up removing some sort of a check valve on top of the gas tank. I think it's supposed to stop fuel flow if the boat turns over. It went bad and was closing off the fuel anywhere above idle.

  6. #6
    Registered John B's Avatar
    My Boats:
    36 skater
    Join Date
    May 2001
    The solution in the filter was probably the result on gasahol. Early season gasoline deliverys containing alcohol can stur up and emulsify the water and crap in the dealers tank and deliver it to your fuel tank. You many have to get the tank and the whole system cleaned out. Consult the dealer. We had a dozen boats needing some major work last spring. The companys picked up the bill.

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