1996 Mercury 75hp fuel problem

Discussion in 'Gas Engines' started by hmcret, Jun 14, 2015.

  1. hmcret
    Joined: Jun 2015
    Posts: 2
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Virginia

    hmcret New Member

    Every tine I run my motor it will run fine for several minutes then big down regardless of how much throttle I give it, when I but the choke it picks up and surges but only for a second and only when I repeatedly push the choke. New filter and I run sea foam in it as well. A good friend recommended spraying QuickSilver Power Tune in the carbs while it was running until it dies then after letting it sit cranking it until it clears. Any help would be appreciated...
  2. AndySGray
    Joined: Jun 2014
    Posts: 296
    Likes: 13, Points: 18, Legacy Rep: 91
    Location: Cayman

    AndySGray Senior Member

    Pull out the plugs after - are they wet?

    What colour are the deposits?

    That might give you a clue if too week or too rich.

    Can you keep it running if you trickle gas into the carb?
  3. hmcret
    Joined: Jun 2015
    Posts: 2
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Virginia

    hmcret New Member

    Plugs are wet but not really coated with black like I've seen in the past. It idles rough and when I put it in gear it goes takes off but I can push the throttle to the stops and it won't go any faster unless I press the choke. or increase RPMs unless in neutral.

    Haven't trickled any gas into the carbs but can keep it running by pressing the choke.
  4. gonzo
    Joined: Aug 2002
    Posts: 16,576
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    Location: Milwaukee, WI

    gonzo Senior Member

    That usually means that the jets are clogged. It needs to be cleaned.
  5. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 497, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    If you have to richen the mixture, she's lean, which as Gonzo mentions, is typical of varnish deposits in the passages and orifices. A very common problem, especially with ethanol fuels and easily fixed with a disassemble, cleaning and new gaskets.

  6. whitepointer23

    whitepointer23 Previous Member

    Have you checked the fuel line squeeze bulb. Make sure it is staying hard while the motor is running. If it is not holding pressure the fuel pump can't keep enough fuel up to the carbys.
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