Q jet Accel pump help

Discussion in 'Street/strip 400/430/455' started by 12lives, Sep 25, 2003.

  1. 12lives

    12lives Control the controllable, let the rest go

    I have a Q-jet on my 'burb. It was "rebuilt" by a professional mechanic about 6 months ago. It got hard to start and I notice that the when I flip the throttle (when cold) there is no squirt from the pump.

    1) why would this happen?

    2) Is this easy to fix on the car?

    - Bill
     
    12lives, Sep 25, 2003
    #1
  2. Schurkey

    Schurkey Silver Level contributor

    This is COMICALLY common. It is practically the identifying trademark of a QJ. (and it may not be entirely the fault of the carb!) You won't fix it without pulling it off, and removing the throttle body to epoxy the plugs.

    Pull it apart and epoxy the plugs for the main wells. Any competent mechanic would have done this already. Call him and make sure it isn't already done. If it isn't, HE OWES YOU THIS SERVICE. MAKE HIM DO IT. This was OLD NEWS fifteen years ago!

    Install a fuel filter in the carb inlet that has the tiny check valve built-in.

    If you still have problems, it's fuel pump time.

    This is why:
    1. Plugs for main wells seep fuel. empties float bowl overnight or over the weekend. Carb has no fuel until refilled by fuel pump. Pump takes a while to fill float bowl since the engine is cranking not running.

    2. If the fuel level drops from #1, the needle comes off the seat. This is an air entry point once the fuel level goes down far enough. IF the fuel pump outlet check valve (s) arent air-tight, fuel back-flows til it's at the same level as the fuel in the tank. And if the fuel pump is above the fuel level in the tank, the fuel pump is full of air. Now you have to fill the fuel line before you can fill the float bowl. The car cranks forever! The check valve in the fuel filter will slow the process of fuel back-flowing.

    3. If you still have problems, you need a pump that has good check valves. Note that the pump may test OK even with a tiny leak at the check valve.
     
    Schurkey, Sep 25, 2003
    #2
  3. 12lives

    12lives Control the controllable, let the rest go

    help

    Thanks Schurkey!!!!

    - Bill
     
    12lives, Sep 25, 2003
    #3
  4. 12lives

    12lives Control the controllable, let the rest go

    help

    Thanks Schurkey!!!!

    - Bill
     
    12lives, Sep 25, 2003
    #4
  5. BQUICK

    BQUICK Gold Level Contributor

    Bill, it could still be a bad accellerator pump diaphragm.

    How bout after you get it started.....does the pump spray then?

    Bruce
     
    BQUICK, Sep 26, 2003
    #5
  6. 12lives

    12lives Control the controllable, let the rest go

    leak!

    I moved the truck to pull the carb and smelled gas...looked under the truck and gas is dripping out! :( Turns out the 3/8th line had a pin hole rusted through and apparently it was sucking air when I was trying to start it. :Dou: Fixed the leak and it starts fine.:Dou:

    Schurkey, your explaination helped me think that one through! Thanks! :TU:

    - Bill
     
    12lives, Sep 30, 2003
    #6

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