Fuel troubleshooting

[Dan Brown]

Hello-

It's been a while since I posted, but it's problem time!

The symptoms:
-The car has required long crank times for about 6 months (anywhere from a good 3 to 6 seconds).
-Sometimes it's SLIGHTLY easier to start after I've been driving it for the day.
-My LTFT almost instantly go to 25% on both banks and stay there.
-Hooked up a FP guage to the drivers side rail, I'm getting 20psi the moment I turn the engine to "Run" but it immediately drops down to Zero psi.
-Once started, it sits at 20psi.
-Car runs OK, just not great. It has a flat spot @ 2k RPM that wasn't there before


I have an in-tank Walbro 255 that I put in about 4-5 years ago. I have 37lb (or 38?) Delphi injectors on the rails that are probably 5 years old as well.

Due to the LTFT and the 20psi, I'm thinking I have a bad fuel pressure regulator. Does anyone agree or disagree? The only thing I don't know about is the fact that the PSI immediately bleeds off once the key is on Run. That makes me want to blame a check valve somewhere (but I don't know where).

I'd like to keep the repair as simple as possible. I'm willing to get a whole kit if I have to (quick browsing showed the Racetronix was popular) but if I can just replace the bad regulator I'll do that.

Thanks for your input!

[Nasty N8]

GM does not offer the reg by itself you have to purchase the whole sender assembly. But it sounds like you have a bad pump bleeding off pressure or a hose that is leaking in the tank. Iff you do not have a good seal it will bleed off the pressure and not get up to the correct PSI.

[svshawk03]

I had the same problem. And found the gm parts are just junk. I had my fuel system converted over to a c5 Z06 style pressure regulator and it works well so far

[Dan Brown]

Were you able to just pick up just the C5 Z06 style regulator? Or did you have to hit a junk yard and swap out assemblies?

[99RTA]

You can buy the regulator seperately BUT its probably time to swap out the entire assembly for a new one. The firebird v6 pressure regulator that mounts on the fuel rail ALSO fits and is the same regulator used in our LS1 cars. AND NO I"M NOT TALKING ABOUT THE ACUMULATOR MOUNTED ON THE LS1 FUEL RAIL. The v6 regulator fits and is the same one used in the ls1 tank unit. In fact its the same regulator used in ALL GM PRODUCTS since about 99. They just don't want you to know this.Cheap on ebay...........

If you can't find it let me know and i'll post a link.

[Dan Brown]

99RTA-

Thanks for the input. I should be able to find one. My dealer commented that the V6 diagrams listed the regulator separately, but the LS1's did not. Then he told me he could fix my problem for $691 I guess I look stupid?

What aftermarket options do I have for replacing the ENTIRE assembly back there? I know I can do Walbro or racetronix for the pumps, but does anyone make a good project to replace the whole mess in a direct swap (pump, regulator, wiring, etc)?

Thanks again fellas. I've been off the message boards for a while and I almost forgot what a great resource they are!

[Lonnies Performance]

The problem is that aftermarket fuel buckets from parts stores & even the replacements from GM are typically junk. Even the GM senders look to be of the same imported quality of the parts stores. You will not get the same part from GM that is in your car... they now look like the truck bucket with different wiring connectors etc.

Your plastic bucket is likely OK. You just need a regulator & possibly the level sensor. You could buy a good Racetronix pump kit & hot wire setup, plus a regulator & level sensor to essentially replace everything but the plastic part for less money & wind up with a better part.

[Dan Brown]

Thanks for all the replies:

The rubber fuel tube that went from the pump to the top of the pump assembly was torn at the base of the metal bracket that held it on the nipple. The rubber tube that came with the Walbro pump was longer than it needed to be, so in my infinite wisdom 5 years ago, I zip tied the tube to the side so it had a double bend in it. The second bend at the nipple was where it tore.

Now that I cut about 3/4" off to remove the torn section, it goes almost straight from the pump to the nipple, and will hopefully last!