I'm posting this so someone else searching for this info may find it. My search did not turn up any info on the actual assembly of the Bosch electric fuel pump.

The pump parts (held by four screws) can go back together in any position, but there is only ONE position that delivers good fuel pressure! If you forgot to scribe a line across these pieces before you took it apart, there may be another way to tell how they go back together. My pump had some obvious discoloring on both sides of the aluminum stator in the exact shape of the pieces it mated to. Comparing it to the pump body and the suction port, the orientation became clear.

The thickness of the o-rings is important. Too thick, and the parts won't seat completely (no matter how tight you turn the screws). They may look seated, but you will have insufficient pressure and a noisy pump. I had to use undersized o-rings (they appear too thin for the grooves) to make it work. Perhaps the real seals from Bosch are not o-rings, but flat-faced rings?

Cleaning: Acetone worked very well to dissolve the varnish, but it caused the rubber seals in the check-valve to swell. I had to buy a new check valve. It took quite a while for the acetone to cause the damage, so maybe shorter soaking times would be ok. Remove the check valve first, anyway.

-Adam