96z71sas
OBS Enthusiast
Does anybody know the correct fuel pressure for vortec 5.7 with key on engine off and then running I think 60 psi while running can’t find on here anyway having hard time starting think pump or regulator might be bad thanks
Fuel pressure
- Thread starter 96z71sas
- Start date
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60+ KOEO, then turn off the key and see if it holds pressure. If not, you have a leak somewhere like, bad check valve or leaking injector(s)
X-2,,,60-62 PSI pre start. Once started will fall into the mid 50s. Rev the engine, and will go back into the low 60s till RPMs drop.
96z71sas
OBS Enthusiast
Thank you for reply if it sits for few days it is hard to start and it seems to be getting worse when it’s hot or only sitting for less than day it’s fine going to hook gauge on it see what’s going on I want the mpfi upgrade anyway thank you for your time
That's usually a sign of a weak fuel pump. When they don't get up to 60 PSI pre start, the truck gets hard to start. It will run good as long as your not at WOT,,,,and high RPMs. In that situation, the engine starts starving for fuel. It can trip ECM codes (EG, O2 sensor,,ECT.)..
96z71sas
OBS Enthusiast
Yep the other day I opened it up and right before shift like 5000 rpm it sputtered that’s exactly what I think it is weak pump
I have been having my 97-5.7L for 19 years. The first time that the fuel pump started getting weak,it had me so frustrated, I though about selling the truck. I finally learned about the fuel pump, and how these trucks are very sensitive to fuel pressures. Once I replaced the fuel pump, the truck ran grate. No more hard starts,and plenty of power all the way through each gear @ WOT. I think I have replaced 6 fuel pumps in the 19 years. I have gotten to the point, that I can tell when the pump is getting weak. I have had it throw O2 sensor codes before, and after replacing the pump, and clearing the codes, no more issues. @ 256,000+ miles, I still have the OE Spyder, so I can't tell you anything about the upgrade.
96z71sas
OBS Enthusiast
What is a good pump to use I see them for 40 bucks up to 300 I’d like to get an ac delco or gm
Yes, AC Delco or Delphi, only. I had a new FP fail in the first 3 months. It was a cheapo. Don't remember the name brand though.
96z71sas
OBS Enthusiast
I’m at 53 pre start 51 at idle and goes to 56 when I rev it holds steady with key on so regulator good what do you think swap the pump
