AFB accelerator pump check valve

Discussion in 'Carter' started by Aaron65, Nov 10, 2012.

  1. Aaron65

    Aaron65 Well-Known Member

    I'm looking for one of these for a '65 300. I'm having a bog I'm trying to get rid of. Tried two pumps and I don't seem to be getting a really strong shot. It's the check valve in the driver's fuel bowl that keeps fuel from returning to the bowl. Any ideas where I can get one? Thanks!
     
  2. Aaron65

    Aaron65 Well-Known Member

    Found one online...
     
  3. Cliff R

    Cliff R Well-Known Member

    Common problem with the AFB, Rochester 4GC, and 2GC's. I don't use the feed checkball here when we build the Rocherster carburetors. The pump will fill just fine without it. I suppose the AFB would as well, as long as the fuel level is higher than the slot between the pump bore and the fuel bowl.......Cliff
     
  4. Aaron65

    Aaron65 Well-Known Member

    You know, I've had a slight bog (especially when cold) for years. It always got much better when the engine warmed up, so I always have assumed it was because there's no heat riser anymore. I just got to thinking about that little check valve. Thanks for the insight Cliff...
     
  5. Cliff R

    Cliff R Well-Known Member

    The problem with using a check ball for pump feed, is that it is in the bottom of the fuel bowl. Down there it is exposed to debris, and any water that gets into the carb.

    The ball is aluminum on the Rochester carbs, and they ALWAYS show a leak back to the fuel bowl. The later 2GC carbs didn't use the feed hole or check ball, so the factory must have figured out it was a potential problem, and not needed....Cliff
     
  6. Aaron65

    Aaron65 Well-Known Member

    All right, this is getting dumb. Basically, when the engine's running, I have no pump shot. If I put it on the bench, it's fine. Here's what I've done...

    1. Replaced the inlet check valve. It didn't seem to work well without it.
    2. Raised the driver's side float about 1/32", even though it was at spec, just to make sure the well filled. It should fill through the check valve though.
    3. I found a couple of float seats that had larger orifices in them, in case the car was dropping the float level too much running (grasping for straws here).
    4. I adjusted the pump so it started down in the well as far as I could.
    5. The fuel pump has 6-7 lbs. of pressure to the carb.
    5. The gas is way down in the pump well. I checked the pump discharge needle and it seemed OK, but I'm wondering if it's maybe sucking air. EDIT: I replaced the needle and there's no change.

    The pump just won't shoot with the engine running (or at least it's very weak and sporadic). I'm just about out of ideas here. Maybe the carb has some kind of internal vacuum leak where it's sucking air in the pump system...Any ideas?
     
  7. Cliff R

    Cliff R Well-Known Member

    If it passes a bench test it should work on the engine. The only difference being the fuel level running could be lower than the level when it's bench tested. Set the floats so they are exactly level with the airhorn, even if the spec's show a different setting, and see what happens?

    What type of pump is it, leather?.....Cliff
     
  8. Aaron65

    Aaron65 Well-Known Member

    Problem solved! I simply had to stretch the leather accelerator pump a little with a small screwdriver. Works great now. Sometimes things are so easy you overlook them. Thanks for bearing with me, Cliff!
     
  9. Cliff R

    Cliff R Well-Known Member

    That's why I asked about the leather pump seal. I have no luck with those whatsoever.....Cliff
     

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