G54Bstore Posted July 28, 2015 Report Share Posted July 28, 2015 (edited) Still trying to figure out why I got low fuel pressure . Worked on it all day. New walbro fuel pump , injectors clean , all filters changed or deleted... I'm lost. Maybe the fuel pressure reg?I guess I may have got a faulty new pump? New fuel lines.Fuel pressures around 27 at idle.. Gets lower when I boost. Sometimes I can boost and fp goes up. Most times it doesn't and fuel pressure stays the same.It used to run fine. I tried a spare coil and knock box and mas with no changes.Fuel pressure relay bad? Maybe rewire the fuel pump wiring? Fuel pressure reg bad?If I had the fuel pressure I think it would run good...I'm lost at the moment. Thinking I might try to see if my fuel pump can pump enough pressure.. Edited July 29, 2015 by G54Bstore Link to comment Share on other sites More sharing options...
G54Bstore Posted July 28, 2015 Author Report Share Posted July 28, 2015 Fuel pump tests ? Anyone got a good one. .? I was thinking of hot wiring the fuel pump and put the gauge on it see if it can pump more than 45 psi Link to comment Share on other sites More sharing options...
importwarrior Posted July 28, 2015 Report Share Posted July 28, 2015 Start the car then the First thing I would do is pinch the return hose with pliers or something that will NOT damage the hose. check the fuel pressure gauge and see if the PSi goes up. Is your fuel pressure regulator adjustable? Link to comment Share on other sites More sharing options...
ucw458 Posted July 28, 2015 Report Share Posted July 28, 2015 If this is a TBI car with stock injectors and regulator, base idle fuel pressure should be 36 psi. If it's TBI or MPI with aftermarket injectors they may work better with an adjustable FPR set to 43.5 psi. Either way, 27 psi is too low. Link to comment Share on other sites More sharing options...
Crazy larry Posted July 28, 2015 Report Share Posted July 28, 2015 First on the list to cross off is stupid.... what filters did you replace and can you tell me how many are on the car? Link to comment Share on other sites More sharing options...
scott87star Posted July 29, 2015 Report Share Posted July 29, 2015 Focus on the fuel pressure, changing the coil, knock box and MAS has no effect on fuel pressure and only makes you angry (captain obvious speaks!). Link to comment Share on other sites More sharing options...
jeph_tsi Posted July 29, 2015 Report Share Posted July 29, 2015 fuel pressure regulator... importwarrior has it right, and pinching the return line takes only a few seconds so start there. Relay generally is only gonna be on or off, so if it gets power the relay is working. Could be defective fuel pump, but very unlikely as this happened before you replaced it so very likely the original pump isn't bad either. Link to comment Share on other sites More sharing options...
tsi_tom Posted July 29, 2015 Report Share Posted July 29, 2015 (edited) Was the tank rusty? Look at the metal lines. Are they pinched perhaps from a jack? Did you tighten the clamps so much that they collapsed the metal line? Edited July 29, 2015 by tsi_tom Link to comment Share on other sites More sharing options...
G54Bstore Posted July 29, 2015 Author Report Share Posted July 29, 2015 (edited) Gonna run tests on the fuel pump today. Just wouldn't think I got a defective one.Everything else is good clean not rusty or pinched. Thanks for the ideas guys I was just hot and tired yesterday. I'll get it figured out today. Edited July 29, 2015 by G54Bstore Link to comment Share on other sites More sharing options...
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