The Outlaw Kid

iTrader: (1)

The fuel pump went out in my 96 Trans Am so I pulled the rear end, the exhaust, and dropped the tank. I figured how often does a fuel pump go out I'll do it the GM way. I went to autozone and got an airtex fuel pump. I've never had a problem with autozone fuel pumps before, so why not. Plus it was a week from payday.

Well I put probably 30-40 miles on the new pump. Then going from idle to around 2k rpms like normal driving, it wouldn't go it started to stumble but I kept dancing on the throttle and it bounced back. About a another block or so down the road it did it again same thing I danced on the pedal a bit and it came back.

Well I eventually got to where I was going and when I came back it wouldn't start. I wasn't that surprised and had it towed right away. First I took it to a chevy dealer to have it diagnosed. They said my fuel pump and failed agian.

So I had it towed home and ran my own test to be sure. I could here the pump prime but there was no fuel pressure at the rail. So I said screw it, grabbed the grinder and let sparks fly. I changed the pump and it started after a little more work.

Heres the issue I have now its somewhat a hard start and running the fuel pressure is abut 35 psi. KOEO to prime the pump it is about 37 psi. Is this ok? My Haynes manul says 41 - 47 psi at KOEO so I don't think its off by much. But I wouldn't think a new fuel pump would have lower than spec pressure. Or are autozone airtex pumps garbage for these cars?

Oh the fuel filter is new as well. I always change them in pairs.

Rob WS6

iTrader: (16)

Running pressure is around 58-60psi. Your pressure is WAY too low... Get a Walbro and never worry about it again.

The Outlaw Kid

iTrader: (1)

That may be what I end up doing. I'm gonna check the FPR and the lines and see what I find. But in the end I'll probably buy a Walbro.

The Outlaw Kid

iTrader: (1)

Does anybody know the fuel volume spec?

Lonnies Performance

iTrader: (16)

LT1 cars are 43psi, not 58....

Airtex pumps are OK, but not top shelf parts.

Prime pressure means nothing but the pump is working.
Running pressure is all that matters.

The regulator controls the pressure, not the pump.
If your pressure is low, eiter you have an internal leak or the pump is bad.

If it primes & holds pressue, a leak is unlikely, then I would blame the pump.

The Outlaw Kid

iTrader: (1)

My friend had a new spare carter assembly we put it in and it helps but it's still not up there in spec. The assembly was changed so I'm pretty sure the hoses from the pump aren't leaking in the tank. I don't see any gas on the ground when we let it run. The tanks been opened and I have gas cans in the garage so it's hard to tell if the car is leaking by smell. Could the FPR be to blame? Like is it plausible?

Rob WS6

iTrader: (16)

Ah didnt realize you have an Lt1 as this is the LS section.

Yeah 43ish stock, though Lt1's have their FRP on the fuel rail and its replaceable. It is entirely possible that your FPR diaphragm has failed! I would have told you to go there first thing had I realized we were talking about an Lt1 car.

The Outlaw Kid

iTrader: (1)

I had never noticed the LS1-LS2-LS3-LS6-LS7 PERFORMANCE section title. Good too know I guess. Is it okay that I post questions about my Lt1 fuel system here or do I need to only post them in the Lt1 Lt4 section. I figured posting it in the fueling and injection fourm was ok and the Lt1/Lt4 section was mainly for the engines. But I'm kinda new still (I don't post alot, I try to use the seach button). I try to post in the right section.

When I pull the vac line off the FPR the pressure does jump to around 43-45 psi. So I'm guessing its okay. The car seems to run and drive alright though so idk what it is its prolly the fuel line going to the fuel filter though. Just guessing. It doesn't seem to be kinked though I'll have to pull the line off and see sometime.

Rob WS6

iTrader: (16)

I doubt theres anything wrong with the fuel line. And yes the fuel pressure is supposed to rise when you remove the vacuum... that's still too low though, by running it as is you run the risk of leaning it out and possibly ruining your motor.

The Outlaw Kid

iTrader: (1)

So if you were a guessing man would you change the regulator? Up to the test valve everything else is new except the regulator and the lines.