This is a re post from the Chevy truck Teck area. No reponse over there so I am posting it here. I hope no one minds. I will kill the thread on that forum.

I saw a post similar to this but not quite the same. So I am posting my situation.

I have an 89 with a 350 tbi. with stock headers and exhaust.
The problem started at night about a week ago.

It happened once then I drove every day for a week before it happened again yesterday(one of our hottest days)...three times.

I was driving along and the engine died. The starter and engine would turn strong but would not fire almost like fuel or spark starvation. I Let it sit(usually with frustrated and cussing drivers behind me) for a few minutes and it started. It ran for a few more minutes then repeated the process. The third time I threw it in 2 and drove it back home (about 5 miles.. with no problems) thinking it might be the alt going bad.

From past experience I believed it was the alt, so I replaced it and the battery(when one goes the other is usually not far behind.) I hopped in and took off for a short drive(2 miles...mid day) with no problems until I was right at my drive and it dies with the same symptons... only no frustrated drivers behind me this time.

I got back in later in the after noon and drove it 15 miles with two intentional park and stops and no unintentional stops. This morning went to drive it and it started fine then died. Now it will only start after extened rests.

It has new temp and oil sending units(3 mos), new distrib, rotor, plug wires, and coil (10 mos), new fuel pump and filters(1 year), new air filter(2 mos), new plugs (6 mos), new battery and alt(24 hrs).

I put meters on the the alt and battery and every thing looks good with ac, lights, turn signal and stock radio on high.

I checked and cleaned rotor and distrib. contacts and verified coil with ohm meter. I visually confirmed I am getting fire to plugs.

I have not checked vacum but will to make sure computer is not advancing the times and getting whacked out or something.

I am going to check fuel pressure also.

I saw info about heat soak on the starter but mine is turning fine only dropping the volt meter to 9-10 when cranking and for the few minutes it runs charging at 12.5 to 14. I did have an old chevy truck that had similar problems and the starter was shorting under heat but this just seems to be different. More like a vapor lock or fuel starvation or something.

I just feel it is a fuel or electrical heat related problem. Almost like the computer is reading some setting and throwing a switch shutting everything down. I will check timing just to make sure it is correct

ANY thoughts or guesses would be greatly appreciated. I will try a new starter and put a shield on it, if anyone thinks that is the real problem.


Thanks in advance for any help!


-----Next Day-------------

Ok more weirdness. Got in it to go this morning and it started and ran in the drive way fine for 15 minutes so I start to pull out and it dies. Will not crank again.

Called in to take a comp day, changed my outfit, and started checking everything. Pulled battery to reset comp, checked fuel flow, checked spark with inductive spark checker all ok. Shot starter fluid in ran rough for 30 seconds then died and would not restart.

2 hours later around 11:45 am I thought maybe moisture in Distrib. So, I pulled it WD40ed it wiped it out silicone lubed button put it back together and it still would not start.

Pulled number one plug wire but left plug in hooked up external spark checker to a spare plug and was getting no spark on first 3 cranks then it roared to life...and ran...with spark on test plug. I turned it off after 2 minutes and reconnected the wire to the plug and started it again. It ran for about 30 seconds then died.

Again it would not start for almost an hour.

Once more I pulled the wire only...not the pl

 

I'm glad i'm not you Have you tested or replaced the
CAMSHAFT POSITION SENSOR if not try that. The only other thing that I could think of is the MASS AIR FLOW SENSOR. Either of these sensors will cause the type of symptoms that you are describing if they are not functioning properly or are not receiving the correct voltage.

GOOD LUCK!!!!!!
Please post if you figure it out.

 

Mine doesn't have a Mass Air Flow sensor but it does have a throtle position sensor that your comment made me give more thought to. I may replace it.

I'm also going to replace the whole distrib. I understand the ICU/ICM signals the computer when to fire the injectors so maybe it got toasted.

My distr. is under warranty and the guys at the parts store where good enough to give me one to try.

I replaced the starter last night and that did not help.

I also checked the timing and found it was way advanced (20+ degs)so I reset it. I thought this fixed it because I drove around the neighborhood for over an hour last night with the ac, lights, and radio on and it did not cut off.

I got up this morning and drove it one street over and it cut off. I pulled the air cleaner(like that is going to do anything) and noticed the injectors were not pumping during my restarts. Then they started pumping on the attempt that worked. I know I had fuel to the TBI because I checked it and it was flowing with proper pressure. This leads me to believe the ICU/ICM may not be sending proper pulse or some mission critical sensor is on the blink... but which one?

The recovery time was about 10 min. It restarted and got me back home without incident.

Now I am really baffled and can't trust the truck at all. It has been a great truck this is just plain crazy

 

Problem solved....I think....maybe!

First let me say the reason I didn't mention any codes earlier is because there were no codes to mention. Yep, the comp did not have any stored code. It only gave 12-12-12.

I proved that the comp was not the issue by pulling the TPS while it was running and sure enough when I checked the computer I got a 22 - Problem with the TPS at idle. So I was satisfied the comp was working. But why no error code when the Check Engine light came on and the engine died?

A mech. friend convinced me to take the ICM off and let him check it on the ICM testor. I kept arguing with him telling him I had a relatively new distrib. and ICM. He told me to quit being a bullheaded #@$ and bring the ICM to him. So I did. He put it on the testor and ran the test 6 or 8 times and everything passed. See I was Right!

He then applied a high tech heat source(a lighter) to the metal plate that sits on the distrib. plate to simulate summertime running engine temp. He generated what he determined to be a temp close to 200 degr. and then re-tested.

Son of a Bullriders Gun, it FAILED on the fuel injection control test. Bingo that was it. That is why when it died it would have fuel to the TBI but the injectors would not release fuel, yet when I would spray starter fluid it would start and diesel for a few seconds then die.

Then he told me what is now one of the most profound things I have heard in a long time--

A code 12 is still a Code.

Duh, you might say but listen a code 12 means there is no ICM signal and that means an ICM could be bad. Not Always but it was exactly the case this time. I have had ICMs go bad in the past many times but the failures were on the timing side and revealed themselves through other error codes and poor performance. I have never had an injector side failure like this. Heat does mysterious things

No error can be an error!

Some GM engineer worked hard to come up with that computer code!

I replaced the ICM and started it up. No problems. Let it sit in the drive and burn $2.99/gal gas and no problems. Well I went out and drove in small circular paths first through the neighborhood then out and around the neighborhood and No Shut Downs. It seems to be healed but I will have to take a few more confidence building runs to make sure.

Lessons learned (Really Re-Learned. I know them I just tend to forget them):
--There are some people (almost everyone) smarter than me,
--It is always the part that couldn’t be the problem that IS the problem,
--Heat and electronics are a bad mix,
--I REALLY miss the old days of points, plugs, coils, condensers, mech. fuel pumps, carburetors and NO Electronics under the hood.