Fuel pump pressure too low?
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AudiWorld Member
Joined: Aug 2003
Posts: 523
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From: Brooklawn, NJ
Fuel pump pressure too low?
Back again, cleared up the frozen fuel pump problem I posted on 9/15. Yes, it was frozen, as evidenced by cutting the aluminum case open, at the roller imeller and/or bottom bearing. I happened to have an extra FP in my garage (used, ugh). Here's my problem... I stupidly hooked the discharge or output line to the return line (almost the same size hose inside the tank). When the engine would not start, I loosened one of the fittings at the filter and no pressure. I then opened and looked inside the tank, like I should have done in the first place, and traced the correct placement. It runs but I think I either messed up the internals by 'backflushing' or the FP pressure is too low. I made a pressure tester by drill and tapping a small fitting on one the banjo bolts on the fuel dizzy. I read 40 PSI or approx 2.5 bar. As soon as I hit the accel pedal, it acts like it starving and ready to die. By nursing the acelerator I can get it to rev up and it still maintains the same pressure. Is this too low? Before I shell out 200 bucks I'd like to rule this out. Also, did anyone ever install a 'booster' pump in line? What pressure does it take to operate the mechanical injectors? Besides Megasquirt or 034EFI is there a cheap way to convert to EFI?
Thread Starter
AudiWorld Member
Joined: Aug 2003
Posts: 523
Likes: 0
From: Brooklawn, NJ
Update
Installed new fuel filter and rigged a pressure tester on the discharge end of the filter. Pressure went up to 50 psi. Looks like that is the optimum pressure for mechanical FI. The EFIs look like they run higher pressures. No inputs on this??
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