How can I tell if my fuel pump is bad?

Discussion in 'Outboard Maintenance' started by snooknreds2, May 2, 2009.

  1. snooknreds2

    snooknreds2 Well-Known Member

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    So i think either my fuel pump is bad or my carb needs to be cleaned. How can I tell which one it is?
     
  2. islander1225

    islander1225 Well-Known Member

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    EXPLAIN WHAT THE MOTOR IS DOING? SO WE CAN TRY AND DIAGNOSE FOR YOU.


    ALEX
     

  3. snooknreds2

    snooknreds2 Well-Known Member

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    Alex, I am sorry about that sometimes I forget that no one has ESP :D


    Here is what is going on http://www.microskiff.com/cgi-bin/yabb2/YaBB.pl?num=1239765184
     
  4. Gramps

    Gramps Living & Dying in 3/4 Time

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    See my post on your other thread.  Also it may be worth cleaning the carb (fuel pump is part of the carb), it is not difficult.  I bought a full rebuild kit; gaskets, needles, springs, fuel pump diaphragm... Genuine Mercury Parts $55 but brings peace of mind and more intimate knowledge of my engine.  Just DO NOT try and replace the thermostat, the bolts will break!  :mad:

    See the parts diagram: http://www.crowleymarine.com/mercury_parts/3236/120.cfm
    Merc. Part #8237072 Carb Repair Kit
     
  5. Brett

    Brett > PRO STAFF <

    A simple way to check your fuel pump...
    this I've done before. Remove engine cowling.
    Disconnect the spark plug wires to prevent the engine from starting.
    With fuel line connected to the motor, squeeze the bulb until
    you hear fuel filling the carb float bowl. Disconnect the fuel hose
    that connects the fuel pump to the carb at the carb end.
    Put your thumb over the end of the fuel line to seal the end of the hose.
    Have another person pull the starter cord to rotate the flywheel a few times,
    while you maintain the seal over the end of the hose.
    After spinning the flywheel several times, aim the end of the hose into
    a gas resistant container and release the pressure on the end of the hose
    with your thumb. If a stream of gasoline squirts from the end of the hose,
    the pump seal and diaphragm are okay. Reattach the hose back to the carb.
    If no gas squirts, squeeze the fuel bub while aiming the hose into
    the container to make sure fuel is present. Reseal end of hose with thumb.
    Spin flywheel again several times. Check for squirt. No squirt, bad pump.

    I don't remember reading how old the motor is,
    but anything over 5 years probably needs a carb rebuild anyways.
     
  6. snooknreds2

    snooknreds2 Well-Known Member

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    Brett I think mine is different. The fuel pump is on the side of the carb and there is only one hose coming into it. This hose leads directly into the fuel filter bowl. It is a 2004 Merc 25 HP


    I got the carb rebuild kit and it comes with a new fuel pump and manifold ($82 with tax) so I will just replace it while I am at it. MAN I HATE rebuilding carbs and this thing came with a gazillion springs and small parts.
     
  7. Gramps

    Gramps Living &amp; Dying in 3/4 Time

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    Snook - Just go slow. I laid out all my parts on a workbench covered in paper towels.  Only took about an hour from stripped down to reinstalled.  The parts diagram helped tremendously.

    Good Luck and let us know how it does.
     
  8. Brett

    Brett > PRO STAFF <

    I see what you mean, carb bowl and diaphragm pump connected,
    best solution is to do a complete rebuild. Have fun.

    http://www.crowleymarine.com/mercury_parts/3236/110.cfm
     
  9. snooknreds2

    snooknreds2 Well-Known Member

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    OK so I got the carb off.  Which turned out to be more involved than I thought it would be.  The choke mechanisim will be fun to put back on ;)  Then I had to take off the starter to get to the nuts holding on the carb.  Then there is this electric looking thing on top of the carb.  Wires looked like a B&*%CH to undo so I just unscrewed the base.  Now I have a fresh can of carb cleaner and off I go!!!

    Will update latter on!!
     
  10. snooknreds2

    snooknreds2 Well-Known Member

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    so I think I am all good now. Test at the ramp will tell...details to come
     
  11. snooknreds2

    snooknreds2 Well-Known Member

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    So now it idles great!!! Took it down to the boat ramp and put the boat in the water still attached to the trailer. Start it up and it idles great. Put it in gear and it idles great. Back in neutral give it a fist full of gas and it smokes (I put allot of oil because of the water that passed through earlier) but it revs up like it should. Back at an idle, put it in gear give it gas and.... it bogs out. Try it several times adjusting the only screw I have access to.

    Only thing that I can think of is that the screw that holds on the bowl had another screw inside of it. I tightened this screw all the way down because it seamed to be that way when I took it apart. Is that the "high" screw and I need to loosen it a quarter turn? I am not sure where to go from here. This is why I hate carbs. I can rebuild them but can not tune them for shizit!!!
     
  12. snooknreds2

    snooknreds2 Well-Known Member

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