fass makes p0089
 

put fass on 01 duramax.with pump running get p0089.turn pump off runs fine with no code.Do I have to high of fule pressure ?Any help would be great

Sounds like the pump is pushing too much fuel for commanded vs actual. Do you have a pressure gauge? did you buy it new or used? If used is it the right one for the truck or was this on a ford as an example? :pca1:

10-12 psi is what you should have going to it.

what is your fuel pressure right now?

the system is new for a duramax.just put guage and regulator on and turned it down to 5psi.seems to be fine so far.is 5psi to low?

no. The stock system was running at a vacuum.