Lifted07Sierra

Car hasn't been started in about 2 weeks but was running like a champ the last time it was started.
I go to start it today and it starts for about 2 seconds and then dies. I then go to crank it over again and all it will do is turn over unless I start pumping the gas if I do this the car will start and will stay running as long as Im pumping the gas but it dies the second I let my foot of the gas.

Also it smells very rich and sounds like something is off in the sound to the exhaust almost like a miss but I can't be sure.

No codes at all

Lifted07Sierra

Yea I pulled them from the DIC.
Picked up fuel pressure checker. Will see what that says in a bit

What's everyone's thoughts on bad TPS?

It's odd that it starts if I pump gas and stays running aslong as I'm giving it gas but dies the second I let off. If I don't pump gas it won't start

Bill Curlee

Codes!! Codes!! Codes!!

Lifted07Sierra

I've checked again there are NO codes except for wheel sensors that aren't there anymore.

I got a fuel pressure checker and hooked it up while I turned the key to on pressure went to 55psi. When I started the car while pumping the gas it would go up to 60 but go to 45 and bounce back and forth very fast. Should the psi be steady and not bounce?

Other than this I dont know where next to check. Makes no sense it was just running fine 2 weeks ago the last time I took it out

Bill Curlee

How did you check the DTCs?? Using the DIC?

Do you have a security light on in the IPC?

BC

Lifted07Sierra

Yes using the DIC just like the video shows.

And what is IPC? I've had the security issue before and it wouldnt start at all. This problem has something to do with fueling or spark Im guessing. Because it will run if I pump gas pedal and keep some gas into it, if not it dies

Bill Curlee

IPC = Instrument Panel Console

If,,,,,,,,, you have no spark or fuel injection control, you would throw a P-0200 DTCs Pumping the accelerator doesn't add fuel like in the old days but,, it tells me that your getting too much air or too little fuel.

Check your fuel flow. If you remove the Schroeder from the fuel rail and attach a line to the end.. Allow the fuel to flow in a container and make sure that you have the VOLUME necessary to maintain engine operation. Sounds like its lacking.

BC

Lifted07Sierra

Just pulled pass side first 3 spark plugs and they are black very black with a tad bit of residue on electrode and around ring. They are also wet and wreak of fuel

Bill Curlee

Drop in some new plugs and see what happens.

BigGun

Hard to believe that is not throwing any codes.

Bill Curlee

OP Is your PCM stock or tuned???


BC

cdkcorvette7

From his profile:

OP, call your tuner and ask them if they tuned out any DTCs... With the symptoms your describing you should absolutely have some codes.

Lifted07Sierra

Changed plugs and car starts without pumping gas but still doesn't idle right and it wants to die. I tap on gas and left off and car will die.

I already know for sure tuner didn't turn off any dtcs

But we know its running better with new plugs but s having an issue. What should I check next?

And again car ran perfect and idle just fine last time it was started two weeks ago.

Couldn't be a broken valve spring?

cdkcorvette7

Sounds like you're still running very rich. Any signs of gas on your new plugs? Do they smell like fuel?

Yes it could be a valve spring...

Lifted07Sierra

Ok pulled some codes
C2120
U1300
U1064
U1096
U1016
B2860
B2282
B2284
U1255

Checked pass side valve springs and from what I can tell none are broke but they are dual valve springs so I cant be certain that the inner spring isnt broke any easy way to tell?

Started it up again and it idles fine until I rev it then it wants to die but just sputters around 500pm for a few seconds and then dies.

Does this sound like it could be a broken valve spring still? it revs up great no sounds or signs of it having an issue reving but when the RPMs come back down it struggles to stay running

Lifted07Sierra

No Ill go pull one right now and see if it smells.

Any reason it would be running just fine then all of a sudden rich while its only been sitting in my garage.

And like I asked in previous post if theres an easy way to find out of the inner spring on a dual spring is broke please do tell.

Lifted07Sierra

Yea I've known about that problem. I'm getting to that but that has nothing to do with the issue I'm having now.
If new plugs made it run better but still dies and idles alil odd what could possible issue be

Lifted07Sierra

I totally agree but its been throwing that U1255 code for about a year now. I've checked the wires before and found nothing, I was going to tear into it in a few days but now this.

So you're that confident that this is the problem that you can't think of anything else to check?