red89c4

my 89 with no mods L98 TPI has been sitting for about a month. i drove it yesterday about 5 miles round trip with no issues. i drove it to church this morning with no issues. after church when i started it, it would start and run for about 3 seconds and then die. it did this about 5 times and then finally stayed running about 2 miles to a restaurant. after eating it began the run and die routine again, after nursing it home I plugged in the code reader and it seem as if it did not recognise that the code reader was plugged in, as the SES light would not flash, not even a code 12. kind of led me to believe low voltage. tightened the pos batt cable and the SES light flashed a code 12 only. cranked it and let it idle for about 5 minutes, no issues. i thought that the problem was solved.

went to drive it to my inlaws cranked fine, idled fine, died after about 25' in the driveway. barely got it back in the garage. i thought at first that it was running out of fuel, but now i am leaning toward the ign side. i have not hooked a fuel pressure gauge to it but i will. i did push in on the schrader valve on the fuel rail after returning from the inlaws and it had pressure on it. i dont think that i will find the FPR bad because if it is a fuel problem it is running as if it is lean as opposed to rich.

as far as i know this car is stock with normal tune up maitenance performed and fact injectors. i bought the car with 75k and currently has 105k.

if it is an ign problem it is going to be bigger than a leaking plug wire. maybe like the ICM or PCM.

where would you start?

AirForceOne!

If she has the original 24 year old injectors with 105k on them, that's where I'm placing my bet!

cohocarl

Hear the fuel pump like usual when you first turn the key on before starting engine for a couple seconds? Not sure if Autozone would check the fuel pressure, but might want to rule that out.

MrWillys

When the key is turned on does it have a steady ses light on?

red89c4

key on not running it has a steady SES light. when i plug the code retriever in the only code that flashes is a code 12. with car running there is no SES light. in other words no codes.

i just cranked it up and it idled and revved up with no misfiring or stumbling. i did not allow it to warm up. i feel sure that if i allow it to get up to op temp it will start acting up.

i alsoshould have mentioned in my first post that the fuel computer reset on its own ( i kind of attributed that to the loose batt term )

soooo...talked to me about ICM. symptoms and diagnosis

hooked073

check fuel pressure when car will not start. also buy yourself a spark tester 4 bucks at most part stores. if you have fuel pressure check for spark. I always like to do a volume test also to see how much fuel the pump is putting out or if there is a restriction. This can be done by removeing the shreader valve putting a rubber house over the fitting and running it into a clear bottle. you shsould get a nice steady stream untill the pump shuts off.

Cliff Harris

The ICM will shut itself down if it gets too hot. Make sure you have THERMAL (not dielectric) grease under it. If you buy a new module it usually comes with the correct grease.

A friend of mine had a "dies when hot" problem. It turned out to be a bad crimp on one of the terminals attached to the spark coil. He soldered it and never had the problem again.

red89c4

update, i cranked the car and let it get hot. finally got it to act up again. had the spark tester already hooked up and it showed positive for spark.

sooo, lets go to something other than the ICM. MAF? Injectors?

Cliff Harris

You promised us a fuel pressure check in post #1. Are you going to let us down? ;-)

91tpiman

+1 for a bad injector too. Test them all for ohms and report back

red89c4

thanks for sticking with me guys. i had to work 11hrs today, did not have a chance to work on the car today. i will try to get by oreillys tomm to get the gauge and then check the presssure friday. if i dont get this done by friday it will have to wait until next wkend. this wkend i am going out of town to work on my dads camino.

i have read enough posts to know that if i dont check the FP you will not help me anymore.

whatever i do i will post if you will stay with me. thank you

red89c4

results from FP check

key on 35psi for 2 seconds then leak down to zero within 1 minute

car running 35psi, car off leak down to zero within 1 minute,

key on 22psi for 2 seconds then leak down to zero within 1 minute,

car running 35psi. car is now sitting at op temp in an attempt to duplicate the heat sink issue that started this problem. i will report back

red89c4

update...base timing was checked to verify 6' after plugging esc back in i was watching the timing light on the scale when the car started acting up. just as the 235 fan came on the car stumbled and finally shut off. while it was doing this the timing mark went somewhere off of the scale. after grinding on the starter the car started and ran again with no issues.

i checked the resistance on each inj while hot and got a reading between 17.2 and 17.6 ohms.

i also cranked the car at one point with the MAF disconnected and after searching for an idle speed the car did smooth out and idle.

Cliff Harris

The may or may not be bad. If the check valve in the fuel pump is leaky then you will get this symptom but it won't cause any problems. If you're losing pressure because you have a leaking injector then that is a problem.

One more test you can do is to disconnect the vacuum line to the fuel pressure regulator while the engine is running. You should see the pressure go up roughly 5 PSI or so. This simulates the low vacuum you get at WOT.

Also check for fuel coming out of the fuel pressure regulator while the vacuum line is off -- the FPR diaphragm is leaking if you see fuel.

red89c4

it will now be 2 wks before i can work on it again. i am now at my parents "resealing an intake manifold with a vacuum leak" found the brake booster vacuum line loose at the carb. a simple repair that made my father happy. mean while i still have a sick 89 vette.