Thread: Looking for some help with this beast

Did you look up what stock fuel pressure with stock injectors is supposed to be at idle?
70 psi seems high to me.
The fuel rail with the circle was an update, like a small resevoir to help keep rail pressure more constant if I recall correctly.

Originally Posted by 231FUN

Did you look up what stock fuel pressure with stock injectors is supposed to be at idle?
70 psi seems high to me.
The fuel rail with the circle was an update, like a small resevoir to help keep rail pressure more constant if I recall correctly.

Well I heard 70 was normal. But I also heard 43 at idle was ideal. So I'm not positive which one is right lol. And thats what I heard as well about it being used to help keep pressure more constant.

Originally Posted by Fivefingerdeathpunch

That fuel rail is from like a 97 model year, I don't know exactly what it does but it just holds more fuel there and likely does something to fuel pressure.

70 psi of fuel pressure sounds really high also. Not sure if rail related, swap your 99 fuel rail on and see if anything changes.

See what the injector duty cycle is, injector ms doesnt always mean they are running static. If you are still only at 75-85% duty cycle, you are not running static with it at 18ms.

And seeing -22 LTFT while driving isnt right, it should not be trying to always take away that much fuel.

That rail is from like a 97? It came on a stock engine straight out of an 04 Impala SS Indy 500 edition. My 99 rail didn't have that extra circle piece. I'll have to get home to replace the fuel rail sometime.
And 18ms I am understanding is static on stock injectors/pump? And the log taken of me driving showed that as soon as it hit 18ms and was commanding -12.5LTFT it started running lean.
I find it weird that the car is telling the injectors to open longer (more fuel), but then see's it's rich (pulls fuel), then can't keep up with command. Like it is confused lol

Pretty sure the fuel rail with the circle was one of the changes for 01, I have an 02 that came with one stock and have seen 01-04 built l67's with them.

My friend that tuned me was watching 02 readings and showed right where the readings start saying it's running lean. But no, I don't have a wideband which I understand does make it harder to prove it's leaning out but to my understanding a wideband is not the only way to see if it's leaning out? I am not a tuner so I can't tell you exactly what he looked at to see where/when it is leaning out. But from how I understood it, right at 18ms pulse width knock started creeping up and the 02 was reading lean from how it was explained to me.

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.

Just my ear. I was going to try and use a screwdriver to try and pin point the noise but saw the time and realized I had to rush off to work real quick. I am quite confident thats where it was coming from but I will double check as soon as I get a chance, which hopefully will be today after my classes are done! Since I get out just before the sun is down today =P lol

Originally Posted by Ginseng

Just take a flat head screwdriver and put it against it and putyour ear to the end of the screwdriver.

Just did this. Definitely a clicking noise in the FPR, the same noise/tone as the rest of the fuel rail. Then the disk has a lower pitch clicking noise with an added distinct metallic tinking noise. And the injectors sounded like the noise in the FPR and rest of the rail.
And it does look like I have the lines hooked up correct and not backward. Although they don't say on them which they are, the line with the metallic sheathing on it is going to the return which matches with a picture of someone's engine bay from the forums that I have.

Originally Posted by REDCOMPG

So are you going to swap fuel rails and see if your problem continues..

Probably. Looks like the step I need to take. But it's at my house and I'm at college right now so the results won't be found out until a little later this week when I can get home for Thanksgiving.