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  1. #1

    Keihin Fuel Pump - Leaking Air

    I have posted a couple of times regarding my 99 SLTH bogging when accelerating above idle. Well, I think I have found the problem. Actually, I had a combination of problems. My fuel cap had a hole in it, and now I have discovered my fuel pump is leaking air.

    Question - My fuel pump should not leak air between the two parts secured with the torx screws, right?

    Right now, I can not hold pressure on my fuel pump and I feel air leaking out between the pump cover and check valve block. a couple of weeks ago I installed a carb kit (non OEM). It included parts for the pump. However, I kept my old parts just in case. I can not get the fuel pump to hold pressure with the original parts or the rebuild kit parts.

    Thanks to John Zigler, I did get a set of carbs that work. Now I just need to find a Keihin fuel pump for my original carb set.

    Thanks again John Zigler for sending me working carbs !


  2. #2
    how did you check your pressure on the fuel pump? I am having similar problems and do not no what is exactly wrong.

  3. #3

    I discovered an air leak when I tried to pressure test my dual carbs. I plugged the fuel return port of my MAG carb then connected a hand pump to the inlet port of my PTO carb. The carbs would not hold pressure. I thought I heard the air leaking around the carb pump.

    I removed the carb pump and tried to pressure test the pump. The pump leaked air out between the pump cover and check valve block. However, I don't think this was the right way to test the pump. I think the pump must be attached to the carb for a proper test. Then, after tightening everything again, I pressure tested my carbs again. This time the carbs held pressure with no leaking.

    I am convinced I was dealing with an air leak. When I had both carbs on the bench my original carbs would not hold pressure. The carbs that John Zigler sent me held pressure.

    For some reason, after taking my pump apart and then back together, my carb seems to be ok. I did not get a chance to put the carbs on my ski, I'll do that today.

    Everything I have read indicates a lean condition if you bog/die trying to accelerate above idle. I have seen two types of problems accelerating above idle.

    1. LEAN - Bogging and or dying accelerating above idle. Using the choke may help get through it. Using the throttle just above idle too long, the ski may suddenly die or die when accelerating.

    2. RICH - Stutters accelerating above idle but does not die. Using the choke makes it worse. Idling too long then trying to accelerate with a stutter, the plugs get loaded up.

    These two conditions sound different too. The lean condition falls flat quickly while the rich condition makes it's way through and finally accelerates.

    I hope some carb guys can correct me if I am wrong here.

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