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  1. #1
    Seaman Apprentice
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    Default Primer Bulb won't stay hard.

    I have a 2 stroke 1990 mercury 90 horse, and whenever I go to pump the primer bulb, to get fuel to the motor, the bulb will not get hard, you can keep squeezing it, What are the symptoms of something like this? Thanks

  2. #2
    Admiral Barnacle_Bill's Avatar
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    Default Re: Primer Bulb won't stay hard.

    Could be as simple as a bad check valve in the bulb. Replace the bulb. Check all your fuel lines for cracks and replace as necessary.
    "A manual is a cheap investment"
    Fair Winds and Following Seas
    Bill
    PTC USN ret

  3. #3
    Supreme Mariner
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    Default Re: Primer Bulb won't stay hard.

    Weaver, It could also be a bad diaghram in the fuel pump. This allows raw gas into the crankcase, and will lock up the motor if it builds up too much.

  4. #4
    Petty Officer 1st Class tysonnathan's Avatar
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    Default Re: Primer Bulb won't stay hard.

    Quote Originally Posted by *WEAVER* View Post
    I have a 2 stroke 1990 mercury 90 horse, and whenever I go to pump the primer bulb, to get fuel to the motor, the bulb will not get hard, you can keep squeezing it, What are the symptoms of something like this? Thanks

    sounds like you already have the symptoms
    could be a lot of things:
    The pickuup in the tank has come off or is not sumberged in gasoline
    blocked or broken in fuel line
    the check valves in the primer bulb are not working correctly
    etc.

    I would replace the bulb and see if that fixes it first... then start checking other things.

  5. #5
    Lieutenant Junior Grade hkeiner's Avatar
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    Default Re: Primer Bulb won't stay hard.

    The primer bulb never really "gets hard" because the fuel pump is sucking (rather than pushing) fuel through the bulb so there is no pressure being built up in the bulb. If the bulb is getting sucked flat and such, then that is a better indication of a restriction in the fuel line.

    To be more certain that you have a restriction in the fuel line or related problem, you can consider using a vacuum gauge to test the system. The below linked thread contains a guide for how to do this.

    http://forums.iboats.com/mercury-mariner-outboards/primer-bulb-goes-flat-merc-150-a-261581.html
    1996 Mercury 150HP V6 carbed outboard motor and Maxum 1900XR bowrider boat

  6. #6
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    Default Re: Primer Bulb won't stay hard.

    Thanks for the help everybody. I probably didn't explain myself real well, my other boat I had, had a 2 stroke engine on it, and when I would first go to pump the primer bulb, after a couple of squeezes, it would get full. This one I have now, when I do that, you can keep squeezing it, and it will never get full. But I will try messing with the pump, and possibly put a new fuel line on it and connectors on it and see if that helps.

  7. #7
    Lieutenant Junior Grade hkeiner's Avatar
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    Default Re: Primer Bulb won't stay hard.

    A fuel line restriction would not result in the symptoms you now describe, so never mind about the vacuum gauge tests. If the carb floats/valves are leaking or you have a hose leak between the bulb and the carbs, you would see the fuel gushing out somewhere. If you do not see this, I would conclude that it is the bulb that needs replacing. If replacing the bulb does not fix it, I would then consider the other good suggestions already mentioned in the earlier posts.

    Just my thoughts...
    1996 Mercury 150HP V6 carbed outboard motor and Maxum 1900XR bowrider boat

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