Changed fuel pump

[LS1CHEYENNE]

I changed the fuel pump (what a pain in the ass !&#33 and unfortunately it still does the same thing - tries to start , runs terribly for about 2 seconds and then dies. The fuel pressure gauge does the exact same thing - jumps up to about 12 pounds and then nothing . A friend of mine found some info on the web about a 99 Corvette that was doing the exact same thing and it turned out to be the regulator . He was wondering about the regulator and said he'd read that it was in the fuel tank on the F body cars but I read that it's the disc shaped object between the fuel rails on the 98 LS1 where the fuel line comes in from the tank . Did the Trans Ams have fuel return line or was there just the evap line reading tank pressure ? I'm thinking that if the evap system is reading a fault , then the computer will shut down the fuel pump . I will say that my oil smells a bit gassy . How could my truck have been running for almost 6 months if the fuel lines and regulator were wrong ?! I've got to say - I feel pretty damned lucky that I ever even pulled this swap off and got it running ! Thanks for all replies .

[COWL327]

My 99 NBS 5.3 did the same thing but it was intermittent.I replaced the regulator and it worked.If it smells gassy under the hood Thats gotta be it.Im guessing this was a used donor that might have set long enough to varnish up or get something in the lines.

[RedHeartbeat]

Obvious question. Is the fuel filter dirty? Do you have a return type fuel system or does it only have the one line to the fuel rail? Have you checked the fuel pressure at the line before the fuel rail? Have you checked the pressure before the filter or directly at the pump outlet at the fuel tank? Maybe something is plugging your system up. Once again I must ask what the probabilities are that you got gas from a fuel tank that went under water during the flood. It may not be water but something else in the fuel. I'd check the fuel pressure at the rail first and work my way back from there until you find a point where you have the required 58 lbs of fuel pressure. What do you have for a fuel pressure regulator between the fuel tank and the fuel rail. I run the 2000+ Corvette internally regulated fuel filter in mine. I cut the lines at the stock location and plumbed the return pressure there.

[rckrzy1]

My fbody and every GM vehicle I have has the regulator on or very near the
rail. And when they fail the diaphragm usualy lets fuel in the vacuum line on the
reg.

[RedHeartbeat]

Just got off the phone with him and he has the identical fuel rail setup that I do. There isn't a vacuum regulator on the fuel rail, it is just spring pressure only. He is going to check the fuel pressure at the filter since he is still running a stock V6 filter and no regulator. I suggested he install the internally regulated fuel filter from the 2000+ Corvette. We'll hear something before too long, I am sure.

BTW, JD, the WIX filter number is 33737 and is $41.99 at OreillyAuto.com.

[LS1Nica]

Hey Red I was still running the stock V6 filter on mine and i ran fine. Well of course it was a new filter but I mean that didnt give me any problems. I sent mine fuel rails to S&P to get modified so Im pretty sure that means I got the F-body on rail regulator right? That part number you gave though, is that for the filter and regulator? Thanks.

Hey Cheyenne I hope everything works out man. I know you just wanna get your truck running and all, but can you post some pics of it. I got a Cheyenne too, everyone else seems to have the composite headlight on their 1500s.

[RedHeartbeat]

The filter has a built in regulator that returns the excess pressure back to the fuel tank. I talked to him again this a.m. and he has other problems. He has only 12 lbs of pressure before the fuel filter. He is either got a cracked fuel line in the tank or it's not getting 12volts of power to the pump.

[RedHeartbeat]

Well, the tank line wasnt cracked. The coupler hose from the fuel pump to the steel in-tank line was leaking, had blown a hole in itself. It must have blown out due to extreme fuel pressure since he didn't have a fuel pressure regulator to return the excess fuel pressure back to the tank.

[LS1CHEYENNE]

First of all , wanted to thank everyone , especially RedHeartbeat , for all of the help . Yes , I finally got her going . I'll reluctantly have to sacrifice myself as the example not to follow ! What a comedy of errors, but at least I"m honest about what I know ( and that ain't much&#33 At least I do have one of the best engines ever built sitting down in my truck and that's reward enough . If I hadn't been in a rush I"d probably have seen that hole in the coupling hose in the tank but , if I"d been smart I'd have tested the unit before reassembling everything . What I can't believe is that this truck has run for 7 months w/o a regulator . I really thought that there was one on the rail . Anyway, truck seems to run really well now and I feel better knowing that maybe I have the correct fuel pump in the tank now (ep381) as well as the correct regulator and fuel pressure . It seems like the power that it had when I first got it running has returned . Also runs fine with the O2 sensors hooked up now (previously , when they were hooked up it would run extremely rich , lope and die ) . I'd like to get some input on that one . IT seems like , initially , sense there was no fuel regulation , that it would have run rich. Is it possible that the O2's sensed too much fuel , tried to lean out , but were unable to ?

[docgreen9]

LS1 don't beat yourself up too bad. We all do the DOH!. I had a similar trouble. I neglected to replace the coupler hose from the pump to the steel line in the tank. Truck ran twice great and then like a dog. Found 12psi all the way back... ended haveing to drop the tank again and replace that little bastard... lol.

Hey at least you got it.. good job!