I'm working on the g/f's truck (97 4x4 S10, 4.3 Vortec vin X), and I think it's got fuel pressure issues. When you key on, it does build pressure, up to about 60 psi according to my test gage, but it immediately all bleeds back off to near zero when the fuel pump prime ends. It takes it a couple seconds to start, but once it starts, it reads about 54 psi at idle, and will jolt up to around 60 and back down if you snap the throttle really quick.
I'm thinking that the internal check valve in the pump may not be closing to maintain pressure, and that the pump itself is only mildly weak. I just put a new Napa fuel filter on it before testing.
Does anybody know what pressure it should be? I thought ~62psi was the target but can't confirm. Is the pressure supposed to bleed back so low after the pump primes? Am I stuck with replacing the whole fuel pump hanger assembly if any of the above are the actual issues?
Thanks in advance for any help anyone can give. I've not worked with the actual Vortec fuel systems before.
'99 S10 Std. Cab Stepside, ZQ8, LS2, T56, Posi 8.8, LS1 front brakes, C5 Z06 Wheels
'97 S10 Std. Cab Stepside, LT1, 4L60E, 2500rpm Stall, Narrowed Disc Brake Posi 8.8