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  1. #1

    fuel pump grommets???

    Anyone know the secret to getting those little check valve grommets that come in the 780 fuel pump rebuild kits back into the holes?


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    A touch of 2 stroke oil on the grommet, and the biggest allen wrench that'll fit. Then push.......

  3. #3
    Ball type? I already pushed one allen head thru the first grommet. These things are a bitch?

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    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Ball type does help prevent tearing of it.

    Lube it, and push it with a wiggle. It'll get in that hole....

  5. #5
    Got it in the hole with a little lube...brute force and ignorance!

    Now...the pump is back together.. I can blow air into all four fittings in the sides and hear air moving thru the pump. I can not physically blow air thru the back fitting which i believe is the pulse fitting. Is this correct? How does this pump work exactly? I have my thoughts on how it might work but would rather not cook another machine finding out if i built it right.

  6. #6
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    The pump operates by the pulse in the crankcase,the vacuum and pressurizing causes the diaphram to move in and out.That motion sucks the fuel thru the PIA check valves and progressively pushes the fuel. You should not be able to blow thru the pulse fitting, and should not be able to suck thru the input or else something is not right.Also if you plug the outputs and only blow into one outlet,no air should leak.

  7. #7
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    There's a proper way to install the check valves. Did you pay attention to which side the marker was facing?

    There's a natural "cup" to the check valve and needs to be installed properly. Otherwise it may not seal.

    Like Dan said, piston upstroke creates a vacuum on the diaphragm. This movement opens the inlet check valve and draws fuel in.

    The piston downstroke creates a + pressure on the diaphragm pushing it the other direction. This closes the inlet valve and forces the fuel out the fuel chamber via the other check valve.

    This repeats over and over for every revolution resulting in fuel pressure.

    The restrictor in the return hose creates a resistence that builds up pressure up to 6 psi at WOT.

  8. #8
    Sweet. then it looks like i got it right. I guess the fuel pumps were my problem then cause when i originally took this pump out i could blow into the pulse fitting and actually hear the diaphram pop in and out. Now i cant blow in it and cant suck air out of the inlet hole....Thanks again guys...If you cant rebuild a polaris using this site then maybe walking talking and breathing are too much for you....and you should live in a bubble !

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