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  1. #1
    Join Date
    Apr 2009

    98 merc efi primer ball collapsing

    Have a 98 merc efi and the primer ball keeps collapsing when I am running near full throttle for an extended period of time. When this happens the motor acts as if it runs out of gas. let the boat sit for a few, the primer ball returns back to normal and the engine runs fine. The ball seems to be in good shape and operates properly when squeezed. The boat is a 98 ranger R81 sport, my thought is venting but I cant seem to find one on the boat, even though I understand there has to be one for gas to flow properly. I left a similar post on the ranger site with no response. Any help would be appreciated, thanks.

  3. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Greenville, SC (US)

    Re: 98 merc efi primer ball collapsing (terryfish1)

    Read through the following post, and ensure that ALL recommended items have been completed on your boat:

    Due to the fact that the primer bulb is collapsing... it's obvious that there is a RESTRICTION somewhere between the BULB and the FUEL LEVEL IN THE TANK.

    Potential causes include:

    -Restricted pickup tube in tank
    -Restricted Anti-Siphon Valve (usually a nipple screwed into top of pickup tube)
    -Restricted or plugged FUEL TANK VENT
    -Collapsing fuel line between FUEL TANK AND BULB
    -Restricted primer bulb (inlet side of bulb or check valve failing)

    Note: Some fuel tanks are vented through the FUEL CAP. A quick/simple way to rule out venting problems is to loosen the fuel cap (make sure it's ATTACHED so there's no possibility of it falling off- and take precautions to prevent water from entering), then see if the problem persists.

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