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  1. #11
    Join Date
    Aug 2010
    Location
    Oyama, B C , Canada
    Posts
    650

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    copied this from another post--similar problem

    "Pulled impellor and it looked fine until I looked at the brass interior...it was worn and spinning in impellor. Repalced and all is good now...Thanks! "

  2. #12
    Join Date
    Aug 2009
    Location
    London, Ontario, Canada
    Posts
    1,187

    Default

    How long have you had the boat. Was it running fine and then it started overheating all of a sudden or slowly over some time? Please give us all the information. What did the impeller look like? How many hours on the boat. Does the engine suck water out of a pail? This is your first post , how about some history.
    2009 21v Worlds 340 Cat
    run your engine after you change the oil
    Doug

  3. #13
    Join Date
    Aug 2012
    Location
    Kennewick, WA
    Posts
    7

    Default

    Okay So the Shop Fixed it this time They put the damn thermostat in backwards (idiots) But now magicaly I have a runnability problem which i didnt have when it went into the shop. When I go above 20mph the engine starts to cut out and if i really get on it it backfires and sputters and wont go above 20 mph. The Shop guy said my carb was gummed up. So I cleaned the carb with no results. This is also odd because when I first take off from a stop it has tons of power and quickly climes to 35mph and then starts to sputter and cough until i Bring the throttle back down to about 35%. Fuel, Spark, or What I dont know.

    P.S. 1991 Supra 351W 4bbl Holley with electric ignition.

    Thanks again guys for the help.
    "None of this will matter when we're famous Rock Stars"

  4. #14
    Join Date
    Feb 2009
    Location
    Minneapolis, MN
    Posts
    3,112

    Default

    I just learned that the OEM water pumps should pump 9 gallons per minute. My original pump came nowhere close to that, maybe a couple gallons a minute. Tried tons of stuff, and eventually replaced the whole water pump. Worked for me.

    Your new problems do sound to me (amateur) like a carb issue, but could need adjustment, a good cleaning, or a rebuild (new seals, etc). There is a quick check you can do on the "power valve" on holleys website if you google it. Have you ever had the engine compression tested? Good luck
    --WakeMikeys 1987 Supra SunSport--
    Thread - https://forum.supraboats.com/showthread.php?t=3630
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    Follow me on Twitter @WakeMikey

  5. #15
    Join Date
    Aug 2010
    Location
    Anderson SC
    Posts
    249

    Default

    I'd say fuel delivery. If it initially accelerates well then starts to cough it sounds like the float bowls are getting low. Check fuel filter(s). That really means change them if they haven't been changed recently. Then do a fuel delivery check on the pump. You will pull the fuel line off at the carb or somewhere after the filters and run a line to a container and see what you have for volume when cranking the engine. You should get a good shot of fuel every other engine revolution, no need to count engine revolutions btw. Just look for a good pulse of fuel and you should get a pretty good volume of fuel in say 15 seconds of cranking. I'm guessing a cup or so. What you want to be sure of is that it doesn't just pump a little bit and then barely trickle, if it does you have a restriction in the supply side of the system.

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