Thread: Looking for some help with this beast

Originally Posted by Shmoke

It sounds like your fuel pressure regulator is bad or tank return line is plugged or kinked somewhere. 70 psi is way too high. Depending on your vacuum your fuel pressure should be around 40 psi at idle.

Check that return line first. Is it possible that you mixed up the lines when you hooked them up? If you don't see a problem with the lines then swap the rail/regulator.

Well I suppose it is possible I mixed uo the return and the incoming lines. I doubt it because I had everything connected and the car would stall after 15 minutes. Found out it would run fine right at 43psi at the rail, then it would drop to 20psi all of a sudden, and then down to 10 and stall out. Replaced the pump with a new stock pump and now I have 70psi at idle. Did nothing other than the new GM stock GTP pump for my 99GTP =/

Would a bad regulator cause problems like this? I've never had a problem with the regulator going bad but if thats the problem that would be pretty easy haha.

Originally Posted by coolone

Injectors tick... But not that little round thing! Injector could be an issue as well as what's been mentioned above.
: )

Yeah, I wish I lived closer to people that could listen and see that I'm not crazy ;P that disk is ticking. I first thought it was a lifter by cylinder 5 but then when I listened closer a few days later I realized it sounded like the other 3 cylinders but got much louder right on that disk. Thats why I was curious what it was.

Now the car idled fine at 43psi with the bad pump, but the pump after 15 minutes would screw up and not keep pressure and the car would stall. Now it makes the same noise as it made when it was only getting about 10 - 20psi at the rail but it's doing that while receiving 70psi at the rail.

Originally Posted by Shmoke

I didn't know that you changed out the pump right when this started. Now I definitely think you have a blocked tank return line or you swapped the two lines.

It could be that you switched the lines at the pump side when you changed it out. That would have you feeding fuel into the tank return port on the regulator through the return line hooked up to the fuel pump outlet. That would push the regulator open to full pump pressure. The fuel filter is producing the back pressure on the fuel returning to the tank through the supply line. Maybe the filter has a check valve inside and the pump has a built-in bypass regulator at 70 psi?

What happens to the pressure when you put load on the engine? If it varies then you have no regulator action and that leads me to believe that you switched the lines. If it remains stable then I think you have a kinked or blocked return line and the pump has a bypass regulator inside set at 70 psi.

Well, I can double check the lines going to the pump canister. But the last person to touch those was a shop. How would I be able to tell which line is what when I'm back there? I never saw any markings on them.

And I was stupid and took the fuel pressure tester back after I found out I had 70psi at the rail which later I realized I should have kept it hooked up and drove to see how everything went..

Also, when I changed out the pump the car ran fine for a while. Idled like it should and everything. Now after I got it tuned was when it started idling weird. But the tune that was put onto my car ran fine on a Daytona 500 car running an xp cam.

When I first got this car even completely stock, at WOT it would pull timing down to 8* even after I put a downpipe on it and it saw no knock. I'm not sure why it would do that because thats when the tune was stock and I had no mods except a catted downpipe and 0 KR.

I got it kinda retuned and now I'm not seeing much knock until about 5500rpms and then it creeps up. And after about 60 there is almost always knock.