Fuel /air mixture problems?

Discussion in '40- & 55-Series Tech' started by okie, Jul 15, 2005.

  1. okie


    Likes Received:
    Dec 9, 2004
    The West
    hey my cruiser has a problem. every now and then when I accelerate on the gas pedal it feels like im sucking in a ton of air into my fuel mixture. The coarburetor guy i just took my carb to asked if it might be the fuel tank sending unit when the tank is near empty it sucks in air because the fuel is low. ( im not sure about that) it was his wild guess. The guy looks like santa clause! Its awsome. anyway wanting to know if any of you guys have had any problems like suckeing in to much air and having it backfire. I really need to figure this out. Im think ing about replacing fuel sending unit or ahving it extended to get all the fuel? new fuel filter, new hose checking and vacuume lines , and replacing the fuel [pump. What do you guys think about an electronic fuel pum better ? or just for a different purpose?

    thanx always,
  2. Pin_Head


    Likes Received:
    Feb 6, 2002
    OC, CA
    It's not too much air. The displacement, RPM and engine efficiency determine how much air. It is too little fuel. If it bucks and backfires when you hit the skinny pedal, it is a problem with the accelerator ump and or transition port. If it bucks and backfires going up long hills with the pedal to the metal, it is a fuel delivery problem (dirty tank, filter, pump, float). Disconnect the fuel line at the carb and see if it can pump 1 cup of gas in 15 sconds of cranking (witht he ignition wire disconnected). If it was a vacuum leak below the thottle plate, it wouldn't idle right.

    The fuel sender only tells you how much fuel is in the tank and has nothing to do with delivery to the carb (unless the tank is empty). Skip the electric fuel pump even if it is the problem.
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