robertearl

My son's LT1 in his 97 Camaro went to idle after 5 laps around the track at MSR. He said if he tried to give it any gas it would sputter and then die. After about 30 seconds, he could give it full throttle again for about a lap and then the same thing would happen.

The tank was full and on the street, he does not have any problem with it. I connected my ODBII and there were no codes. I have not checked the fuel pressure yet but I am thinking it is the fuel pump.

What are your thoughts and what else might I check to help isolate the problem.

Reb

94zrag

If the fuel pressure checks out ok, you might want to check the cat. convertor. When mine was clogged, the car would idle then die if I gave it any gas.

1racerdude

My thoughts would be pump or voltage to the pump,maybe a bad relay,or ign switch. Could be the regulator also but not likely.
Ya could tape a fuel pressure gauge to the windshield and run it till it does it and check the gauge.

RE AND CHERYL

Fuel pump or filter

z28 justin

I had this same problem with my Taurus, it would idle, but give it gas and it would die.

robertearl

Ok here are the pressures. All measured with the vacumn line on.

Pump on 46
pump off 39
at idle 37
at 3000rpm 35
engine off 30
after 10 minutes 29

NVetro

Read 1fstws6's post, he had a similar issue and it was his ICM. The car would just die out of no where when driving.

Injuneer

You need to record the fuel pressure at WOT/max load/max RPM. That eliminates the vacuum compensation, and shows whether the pump can meet the engine's needs at max load. Cruising at 3,000rpm doens't present the maximum load. You could have had enough manifold vacuum to pull the pressure down to 35psi.

Also, let it idle, and remove the vacuum compensaton line (hold your finger over it so there's no vacuum leak). Pump pressure shuold be 43.5psi, with the GM manual indicating anything from 41-47psi is acceptable. Then reconnect the vacuum line and the pressure should drop proportional to intake manifold vacuum. Typically it drops 6-8psi with a stock cam.

Sounds like something may be overheating.... IC Module and the opti optical sensor are two things that come to mind. The coil could also suffer from excessive heat.

robertearl

I pulled the vacumn line off and the pressure at idle was 46 psi. I guess that rules out he pump etc.

Is there any thing else I can try to help diagnose the problem or do I just have to wait untill it is no longer intermittent or a code is thrown

1racerdude

Read my earlier post and the one from Injuneer. That will GET IT DONE.
There is NO OTHER WAY to rule out the pump or electrical to the pump.

We don't just say these things to put you to work we are trying to save ya work. Checking at IDLE ain't hittin on s***. The car doesn't run at idle all the time.
AS you stated it runs at idle but won't rev--- nuff said.

Injuneer

Please take the time to carefully read the answers people are posting. You can only prove the pump is capable of meeting the needs of the engine by measuring the pressure at WOT/max rpm/max load. Checking it at idle with the vacuum line off only gives you a baseline to use when you do the WOT evaluation. If it can't hold within 2psi of the "no vacuum" pressure you got at idle, its not capable of meeting the engine's need.

robertearl

Took it back out where I could run it hard. I made 5 laps with no problem. On the 6th lap at the end of a long hard right hand turn, the enigne went to idle. Fuel pressure was almost 40psi. If I gave it a little gas, it would slow down further and almost die. I let it coast for about 10 seconds and then it would take some gas. I made another lap and the same thing happened again at the same spot.

Oil pressure was good and the temp was about 220.

Seems odd that it happened at the same place twice but then it ran fine for 5 laps also.

robertearl

ttt

robertearl

I checked it at WOT like you asked. I noted the pressure when the problem occured. It appears not to be the pump. What would be the next step to try and isolate this. It is still not throwing any codes.


Reb