4.3 auto 4dr 4wd

Just got it.

Previous owner told me that lately it had been hard to start. Didn't mention power loss.

mechanically sound, idles and low, part-throttle is good and smooth. Seems to have some power. In 4wd climing around the field it does fine. This is to be my new DD.

Cleaned IAC, TB, EGR, and ran seafoam through it. Idle is even smoother, but still a hard start. replaced fuel filter with purolator brand.

Tries to start...seems to try to catch and doesn't. Sometimes takes 3-4 tires. A couple times it took some ether to get it going. Repeated attempts does NOT result in a heavy fuel smell. There really isn't much at all. Subsequent restarts w/i a few hours are typically instant.

No codes.

reset computer. no change.

fuel pressure key on - 52psi steady. Book says it's supposed to drop...?
fuel pressure at idle - 52psi steady

fuel pres never drops below 52 psi.

1/4 throttle or more w/o load FP will increase to 60psi. Revs freely to 3k or better with a solid tap of the pedal.

1/4 throttle under load FP will increase to 60psi.

More than 1/4 throttle under load and FP goes to about 55psi and the truck struggles. Approaching 3,000rpm over 1/2 throttle under load and it feels like it hit a brick wall. Weak.

Talked to a buddy who thought though the pump seems to be putting out adequate pressure, that the volume could be low. It is the original pump with nearing 200,000 miles.

What about a cheaper alternative for the fuel pump than what GM, advance and the others offer...? I've put walbro in F-bodies (we currently have two LT1 firebirds) and they work fine but don't know what pressure they are capable of (255gph @ around 45psi on one of them).

I looked all over the place and did NOT see a FP regulator. The lines look in good shape and the pump sounds to spin up just fine. On key OFF it runs again then stops. Pressure is not bleeding off. After the last shutdown the FP was still about 50psi 2 hours later. My firebird can't do that anymore and that was true right after I put in the new pump on that thing.

It could be the FP and very well could be, but I don't want to change it if its not. Money is tight and I need to start driving this thing, but won't till I can pull into traffic without dying and it will start on the first turn of the key.

TIA for any advice......


Edit.....I read that the FPR is a known issue on these. What I am looking for here is rationale that my pump is providing what it should for prime, but the FPR isn't delivering.....or vice versa.

Looks like I will get a plenum gasket and take a look. Might just replace the FPR as a cheaper way to go for now and if it works....great, if not then I have postponed a future issue.

 

Volume and pressure are directly related. If volume were an issue, you would see the pressure drop. It sounds like your pressure is on the low side.

To verify that the pump is the culprit, you need to remove the fuel filter and, using some various fittings, connect your pressure gauge to the line from the pump to the filter. This should read 60+psi. If it does not, your pump is bad and needs to be replaced.