AXEMAN

Let me just say thanks, first and foremost. I have been on here for a few years now and it has been extremely helpful. My problem is the car is acting like the icm is going. I even got it to throw a code for the icm so I changed to a brand new ac delco icm. No change. Car runs fine until about 45 minutes into the drive. As soon as you stop at a light, sign,etc the rpm's drop to around 500 and then the engine dies. As far as I can tell as long as i'm moving everything is fine. The only codes thrown are 33 and one for the o2 sensor. I know that they are coming from the cam when the rpm's drop that low. I have changed icm,coil, iac, fuel pump, Ac delco opti, fpr, map, plugs, wires checked injectors and yes I have freescan and use tunercat. 2 mondays ago I got it out of the shop from fixing my #2 cylinder having no compression(exhaust valve hit piston and bent). I am not just throwing parts at it although it may seem that way. I have tested all wires and connections(thanks shoebox) including the battery. What else will act like the icm getting heat soaked? I'm stumped guys please help a guy out this thing is killing me. A little background on myself. I don't profess to be the greatest car mechanic in the world but I am pretty good at fixing large airplanes(18yrs) so I am at the least a competent mechanic. Any help would be greatly appreciated.

Style

Can you immediately restart the vehicle after it dies?

mrmint69

I have seen the fuel pump get hot and start to act up. This is happening to me and the hotter the day and the longer I drive the more it dies. If I keep the tank full or its below 90 outide it has only happened once in 6 months. Check fuel pressure it to see whats happening exactly when it dies. I replaced everything you did and it did no good. Did you do the icm spacer mod? Do you have a tune for the mods?

blwnlt4

hmm i wonder if the iac passage could be stopped up with carbon? I dont think lt1s are very famous for this though.

AXEMAN

Yes you can start it but it dies quickly. If you let it sit for 10 minutes it is ok. Not sure for how long. When it has happened I just go straight home. I will check the pressure next time it happens. It is good any other time. Yes I have had the icm spaced for a few years.

AXEMAN

I cleaned the iac passage when i changed the iac. Keep them coming guys

toadies101

try using the fuel pump relay bypass wire by the PCM and jumper 12v to it and drive and see if it dies.. if it doesnt the FP relay is ur issue located under the foot rest panel.. had a 94 formula 10 years ago that had that issue.. stumped me for months..

AXEMAN

I checked the fuel pump relay too. I even have a spare one. I am looking at something else though. I will see if it is the problem later today. Again thanks for the input.

AXEMAN

I replaced the 02 sensors today (delphi) and got the injectors cleaned. It still does the same thing. For the first time today I got it to throw a code while I was driving it. It was a DTC 55 Fuel lean monitor. I am going to look into mrmint69's post and see if the harness is to blame.

Guest47904

Sounds to me like your tank vent is restricted and causing a vacuum in the fuel tank after some run time. Usually this time will vary depending on the amount of air in the tank. Less fuel more air longer time to crap out. Try opening the fuel cap and see what happens.

AXEMAN

I never would have thought of that. I'll have to check my vent tube.

AXEMAN

I think I have a problem with my fuel sending unit. I have a short where the pump plugs in to the sending unit. I found a used one on ebay. I'll try to keep you posted.

Guest47904

Monitoring the fuel pressure while the problem is occurring would have found the problem much easier. Which by the way, mrmint69 mentioned a long time ago.

AXEMAN

Thanks Speedy and I did moniter the fuel pressure and it did not show me that the sending unit was bad. The only way that I could tell that was to look at it and pull it apart. The pressure gage just showed that I was losing pressure. I have put in 2 fuel pumps in 3 months so I did not think that another one was bad. I also had the injectors cleaned, changed filter, etc. Again than for all of your responses.