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97 5.7 mercruiser carbed. Fuel priming

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  • 97 5.7 mercruiser carbed. Fuel priming

    I am purchasing a 97 chaparrel 1930 ss sport. With the 5.7. My question is In regard to fuel priming. The owner has installed an in line priming bulb. Am I mistaken or should this model have a check valve that prevents the need for such a bulb.

  • #2
    Re: 97 5.7 mercruiser carbed. Fuel priming

    There should not be a bulb. Does it have an electric fuel pump?
    83 Sunrunner 16.5 120 merc Alpha 1 drive SOLD 8/1/13

    1996 Crownline 202BR
    5.7l EFI 0f791070
    Bravo I drive

    GMC Yukon tow rig


    • #3
      Re: 97 5.7 mercruiser carbed. Fuel priming

      I will check in that Monday.


      • #4
        Re: 97 5.7 mercruiser carbed. Fuel priming

        Yah, you prime carb motors by pumping the gas a few strokes when they're cold. And no there should not be a priming bulb on there.
        There's no separate check valve cause fuel won't go through the pump backwards. Plus it would have to flow uphill to get out of the float chamber/reservoir in the carburetor.
        Older 4 barrel Rochester carbs had an issue with losing the gas in the res. But that was supposedly made right years ago.
        Over a long period of storage the reservoir fuel will evaporate, making the pump-before-start ineffective. You can find the vent and put a couple ounces of gas in there. Or what I do is to put a couple tablespoons or an ounce of fuel in my carb throat before first start of the season. That will start it up and run it enough to fill the bowl using the fuel pump.
        If the engine has an electric fuel pump you could probably fool it into filling the bowl by turning the key on, listening for the pump to run and shut off. Then turn off the key, pause and do that again. After you have cycled the electric pump a couple of times it will have fuel enough in the carb to do a normal (pump the gas first) cold start.

        Sure, the bulb probably would fill the float bowl, but it's not part of the engine design. It does not belong in a hot engine bay. On an outboard, it's out in a non mechanical open environment. You'd use it a lot and would see if it cracked or started to leak. In your boat it's just a place to have a problem. Take it off. You just don't mess with even the possibility of gasoline in the bilge.
        Last edited by NHGuy; February 23rd, 2014, 08:44 AM.
        87 Formula F223LS, 2016 383 Stroker, 2019 Davis Unified(HEI) Ignition, Quickfuel Marine 750
        Lake Winnipesaukee, NH


        • #5
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          Re: 97 5.7 mercruiser carbed. Fuel priming

          Thanks a bunch!!