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  1. #1

    Default Boat only goes full speed once

    I am having an issue on my 86 four winns 170 Horizon. When I start the boat I can go up to full speed. If I slow down and then try to go back up to full speed it won't go and the engine begins to backfire. The only way I can get it to go back up to speed is to totally kill the engine and restart the boat. Any ideas on what could he causing this?

  2. #2
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
    Posts
    3,819

    Default Re: Boat only goes full speed once

    Well, if we knew what motor, drive, carb ,efi, mpi TKS we might be able to give you a answer instead of a good guess.

  3. #3

    Default Re: Boat only goes full speed once

    Quote Originally Posted by Bt Doctur View Post
    Well, if we knew what motor, drive, carb ,efi, mpi TKS we might be able to give you a answer instead of a good guess.
    Sorry I'm not much of an engine guy. But it's the in line 4 cylinder 2 mericruiser

  4. #4

    Default Re: Boat only goes full speed once

    It sounds like crud in the fuel system! Check out your whole fuel system from the screen on the pickup tube in the tank, then the anti-siphon valve, then fuel line, then gas filter, then fuel pump, gas line, & carburetor!
    My Motto Is:
    K.I.S.S.- Keep It Simple Stupid!
    Or, It Might Get Real Expensive!

  5. #5

    Default Re: Boat only goes full speed once

    I am having a similar problem. I have a 1996 3.0L I/O mercrusier. When I first run it it runs great but when I make the first full turn at full speed it boggs down to 2000 rpms and stays there for a while even with full throttle. Sometimes it will slowly creep back up into 3000s but not running consistently. I have put in new 100% gasoline, took apart the carb and cleaned with carb cleaner and pressurized air, cleaned the fuel line and put in "Heet" fuel additive just in case there was any water in the fuel tank. I am thinking about either replacing the fuel pump or atleast taking it off and cleaning it. I just want to make sure I am heading in the right direction and see if anyone has any other ideas I could be over looking. Thanks

  6. #6
    Join Date
    Jul 2008
    Location
    Northboro, Ma, USA
    Posts
    4,793

    Default Re: Boat only goes full speed once

    fuel tanl pick up issue

    when he stops the issues settles

    could be water could be the pick up screen.........

  7. #7

    Default Re: Boat only goes full speed once

    Where is the fuel pick up screen? What is the fix for it?

  8. #8
    Join Date
    Jul 2008
    Location
    Northboro, Ma, USA
    Posts
    4,793

    Default Re: Boat only goes full speed once

    The pick up screen is at the bottom of the pick up tube, the pick up tube is attached to the gas tank. Ity is where the fuel line connects........

    IF it is this, then the pickup tube must be removed and checked or repaired......it also could be something in the tank other than the screen..

    what can be done is to remove the sending unit from the tank, where the wires connect, and look inside the tank and see what you can see.

    DO NO USE ANY FLAME DEVICES or AC POWERED LIGHTING TO LOOK INOT THE TANK, USE A FLASH LIGHT!!!! LED IS BEST!!!!

    Many who look use a lighter to see............so guess what???? BOOOOOOOM!


    Also make sure the vent line is clear. You should be able to blow air into it from the outside into the tank. Use air only.........

  9. #9

    Default Re: Boat only goes full speed once

    Thanks for the help I will see if I can figure it out and keep ya posted.

  10. #10

    Default Re: Boat only goes full speed once

    Quote Originally Posted by kghost View Post
    The pick up screen is at the bottom of the pick up tube, the pick up tube is attached to the gas tank. Ity is where the fuel line connects........

    IF it is this, then the pickup tube must be removed and checked or repaired......it also could be something in the tank other than the screen..

    what can be done is to remove the sending unit from the tank, where the wires connect, and look inside the tank and see what you can see.

    DO NO USE ANY FLAME DEVICES or AC POWERED LIGHTING TO LOOK INOT THE TANK, USE A FLASH LIGHT!!!! LED IS BEST!!!!

    Many who look use a lighter to see............so guess what???? BOOOOOOOM!


    Also make sure the vent line is clear. You should be able to blow air into it from the outside into the tank. Use air only.........
    Well Stated kghost!
    My Motto Is:
    K.I.S.S.- Keep It Simple Stupid!
    Or, It Might Get Real Expensive!

  11. #11

    Default Re: Boat only goes full speed once

    I had the same issue if I kept it at full speed and went into a turn, it would then bog down.

    Will running a fuel system cleaner through it do anything?



    QUOTE=jlfrye;467558]I am having a similar problem. I have a 1996 3.0L I/O mercrusier. When I first run it it runs great but when I make the first full turn at full speed it boggs down to 2000 rpms and stays there for a while even with full throttle. Sometimes it will slowly creep back up into 3000s but not running consistently. I have put in new 100% gasoline, took apart the carb and cleaned with carb cleaner and pressurized air, cleaned the fuel line and put in "Heet" fuel additive just in case there was any water in the fuel tank. I am thinking about either replacing the fuel pump or atleast taking it off and cleaning it. I just want to make sure I am heading in the right direction and see if anyone has any other ideas I could be over looking. Thanks[/QUOTE]

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