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Discussion Starter · #1 ·
Well, I pulled the fuel pump tonight and replaced the seals. Not a very difficult or time consuming job at all. Probably took me longer to get the friggin thing off the bike as it did to do the actual work.

I've posted a pictoral guide Here. Now, there weren't any instructions and the new parts were a weeee bit different than the old, so I hope that I questimated correctly. Could some of you vets take a look and verify my work?

Thanks,

dj
 

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Discussion Starter · #4 ·
I didn't really know. But for the very small price, and my many years of experience fixing my Bosch fuel pumps, it's cheap insurance.

From the looks of the inside of the pump, there was no buildup. The gaskets were looking pretty weak though, and the plastic gasket in the rear was very concave, which ic probably not a good thing. Either way, it only took about 15 minutes to do. Better than watching network tv I tell ya! :D

-dj
 

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dj,

Good job documenting the procedure with the pics. I think I probably started the fuel pump issue rolling last year. At the time I didn't have a digital camera, so had to write the proverbial 1,000 words in place of each picture.

It sounds like your pump was like mine - the clear diaphram stretched out almost to the shape of its chamber and all brittle and non-elastic. I ended up using all the gaskets in the kit since it looked like the diaphram in the split chamber sandwiches between that ridge in the middle.

Let us all know if you tell any difference in the engine after it's done. I cured some low and high speed problems I didn't even know were problems until I rebuilt the pump.
 

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Now all you need are instructions to get the fuel pump out. I pulled out the fuel pump from my 1997 M900 before selling the frame and engine and that was probably the hardest thing to remove from the whole bike with the possible exception of the triple clamps.

Let us know how long it takes to get it back in place.
 

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I'd tackle writing the instructions, but I'm not sure exactly how I did get mine out
 

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Discussion Starter · #11 ·
You're right. The removal is the unspoken half of the work. Took me forever to wrangle that damn thing off. Installing was a lot easier I noticed...
 

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Glad I could help. Really we should thank Mark1305, he is the hookup.

I haven't done mine yet, I am still fabing my new rear turn signal and plate holder. Then I am going to do the pump, rejet and strap on the dynas from Chris.

Anyone figure out the secret to getting the pump out yet?
 

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i just did mine this past weekend also, and yeah, removing the pump was the hardest part. what i finally did was:

- used a pair of vise grips and rubber hose to clamp the line coming out from the fuel filter.
- wedged a whole bunch of rags under the fuel pump to soak up gas.
- removed the vacuum line on the side of the pump that faces the front of the bike (little clip-type retaining clamp) and the hose leading to the carbs (screw-type hose clamp). soaked up as much fuel as possible.
- removed the top allen bolts holding the pump to the frame. couldn't get a socket or wrench to the nut attached to the bottom allen bolt, so i simply used a screwdriver and some leverage to 'retain' the nut while i eased the bolt off.
- removed the vertical cylinder belt cover. this cleared up enough space to get the pump out. also replaced the rags with fresh ones to make sure no fuel got on the belts.

i couldn't figure out the odd clip-type clamp holding the incoming fuel line on (wasn't sure if i would be able to reuse it after removing it), so i simply left that hose on while rebuilding the pump. seemed to work okay. the gaskets were STUCK on bad. had to use some 0000 steel wool to get the last little stubborn bits off. cleaned everytning off with some fresh fuel and compressed air, and replaced everything just like dj did. was equally confused by the missing 'little clear circles' in the rebuild kit.

everything's great now. i notice things are smoother, with less bucking and lurching, just like mark pointed out. i had some occasional odd high speed power loss that i'm hoping this fix will address also.

but i'm still confused by the whole matter...

how does replacing the little membranes (they are membranes right?) help the fuel pump perform. i could understand if there were a crack or vacuum leak or something, but how does an new piece of plastic work better than an old piece of plastic? and why was the original rubber on the split-chamber side replaced with a plastic doohickey like that used on the other side?
 

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I agree with YellowDuck's explanation. The original diaphrams, especially the clear one that drives the pump on the vacuum side, get stretched and hardened over time and don't pulse as much. Since that pump is capable of flowing twice as much volume as the 900 needs (by some rough calculations using generic fuel/HP/displacement figures) I figure it can degrade over a lonngggg period of time before the engine is affected enough to notice.
 
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