dknechtly

Working on this for friend of mine. A little history... Completely stock car has been very well maintained. It ran and drove fine. She parked it in her garage for over a year and the gas turned bad. I cleaned the gas tank, blew out lines, replaced fuel pump and filters. It starts then dies. I am not getting voltage at fuel injectors per my digital meter. No engine codes. Sparkplugs spark strong. Fuel pump kicks on with over 40+ psi. I by-passed VAT key with resistors. Jumpered the oil pressure switch (pump runs). Still no luck. Any ideas?

alan91z28

you could use a noid light to watch and see if the injectors are actually firing, voltage at the injector means the fuse is ok, the ECM will ground the other side of the injector to actually fire it. using a noid light you can see it flashing indicating the ecm is trying to fire the injector

https://www.summitracing.com/parts/l...iABEgLIAfD_BwE

since you say it actually starts but then dies it probably isn't this, but on a TPI car if the ICM (ignition control module) is bad the ECM will not get signal to all it to sync and fire the injectors... this usually results in not any start... on a TPI 3rd gen you can watch the tach needle when cranking and you will see it won't move, not sure how the vette digital cluster normally acts during initial cranking

dknechtly

Thanks for the tips. I was thinking the voltmeter would tell the story. Maybe I should try the noid light.

65Z01

Does FP hold while cranking & short start period? If not replace the filter.

Bfenty

it's hard to see the voltage spike on a voltmeter. Autozone will lend you a noid light set though. I had a similar issue and my ICM (the controller chip in the distributor) had gone bad. easy and cheap fix, although way too early to say if that's the problem at this point.

dknechtly

The fuel pressure does hold. Even when I jumper the oil pressure switch, the fuel pump keeps running, but the engine still starts the dies.

dknechtly

Sounds like I definitely need to borrow Autozone's noid light. I was figuring while cranking, I would see the voltage do something.

playsdixie

you say the pump stays on...does the fuel pressure stay up when starting and while engine is dying? thinking maybe your pulsator line is blowing out.....

dknechtly

Pressure stays up while cranking (at least with the oil pressure switch jumped). I can't remember with it unjumped (while cranking). I'll have to check again.

Solderhead

The voltmeter can. Backprobe one of the injector harnesses on both wires. set your DVOM to monitor duty cycle. watch the percentage as the car runs and dies. if you've got 100% duty cycle that means the ECM is trying to keep the injectors open constantly to keep the car running. if you see something like this I'd suspect faulty injectors.

What's that? Doesn't seem right because the car starts? I know. I've also had this exact problem on a similar year. confused everyone. the root problem was that four injectors were so bad they wouldn't fire, but they would leak while sitting in place, causing enough fuel to be present to allow the engine to start, but not enough to sustain it running.

Not saying this is your issue, but your symptoms sound very very similar to what I experienced. good luck.

dknechtly

Hmmm... I'll give it a try.

dknechtly

I'm thinking security is shutting off the car. Has anyone used a Passkey II bypass?
https://www.ebay.com/itm/GM-VATS-or-PASSkey-II-Bypass-Module-For-LS1-and-LT1/282700412289?epid=12007509497&hash=item4 1d241f581:g:H~gAAOSw3fZZ6JWY:scSPSFirs tClass!75098!US!-1#rwid

dknechtly

OK, I got the little device that generates the waveform; now to install it. Do I have to remove the whole passenger side of the dash to get to the VAT module? Any instructions? Thanks

dknechtly

I finally was able to get a noid light on it. It was lighting well so electricity is getting to the injector. I think I can mark off the security system as a problem. I also put in new sparks. Same issue; starts then stops. I'm wondering it the injectors are so dirty they are just staying open? I can smell gas out the exhaust.

aklim

What injector do you have? If Multecs, go to FIC and get a reman set.

As to the motor dying, when you fire it up, it starts and then stops. Does it fire up again? Can you take the ignition module to Autozone and have them do a test for you?

dknechtly

Thanks for the input. I'll have to check which injectors they are. Not sure if autozone can check the ecm; I'll have to ask.

dknechtly

It won't start right away. It will try maybe one more time and then it just cranks. I then have to wait. I can't remember how long. When it only cranks over, I still have spark and the noid light flashes.

aklim

Just see which image it falls under. Anything but Multecs can be cleaned. Multecs can be tossed.

No they cannot. It is a specialized thing and they can check the ignition module BUT NOT the ECM.

aklim

That means you are getting signal to the injectors. If you are getting spark, do you have fuel pressure at that time? If you have the right pressure, it kinda points to the injectors.

C5 Diag

Since you are getting injector pulse, fuel pressure and spark and the car SAT FOR A YEAR I'd put a long screwdriver on each injector and see if you can hear it "clicking" while cranking...the injectors might be "mechanically" closed after sitting for so long.... try tapping on all the injectors...maybe not with a 5 pound sledge but maybe with the end of that screwdriver and see what happens !!
EDIT: try spraying carb cleaner into the intake or into a vacuum line...if it starts or tries to start you definitely have a fuel delivery problem !!