VetteBabe1

Thanks! I'll go try that and see what codes I get. The SES light comes on but only because you are letting go of the key, back to "ON". I don't think it's actually throwing a code, but I will check.

I feel like an old fogey...fooling with a broke-*** car on a Friday night for fun.

Just for inspiration, I just strolled into the garage and took a picture of the subject. I just don't think it looks too darn bad for the age and mileage. The paint is at least 12 years old. Now if it just would run (and stay that way). I should post the picture of what it looked like when I got it back. Clearly one person's idea of clean and looking good is very different than another's....

jfb

No need to feel like an old fogey. You are merely an owner of a 20 year old Corvette, just like me! I own an 87 and drive it every day and it needs repair every once in a while. I had to have it painted 3 years ago because it badly needed it, but the car is very reliable and a blast to drive every day! Your car looks very good! Let us know if we can help you with your engine running problem.

kize

Also have you checked the condition of the wiring harness, ignition module and coil in distributer cap?? The harness going to the dist module is a "should replace every 100K". They get old, break down etc. It sounds as if you are getting plenty of fuel- even in the no start condition. If your ignition system is intermittent- you will be driven crazy. A helms manual would pay for itself here- there are plenty of trouble related flow charts in there to help track down your gremlin. I'd have to agree with CFI and Vader - I don't believe a bad IAC would cause a NO run. Another freebe would be to unplug your MAF and test. Bad TPS?? Volt/Ohm meter can be your friend! Good Luck.

bogus

I think you need to really go over that engine harness.

You see, the earlier C4s (and all cars, really, particuarlly American cars) had junk for wire. In 1990/91, the SAE changed the composition of the wire insulation. the new stuff is much more resistant to heat and chemicals. The earlier stuff is junk. It cracks, chaffes, shrinks... you name it.

I would check the harness from the main junction point behind the battery. It's time to either tear that car apart, or give up. It's one or the other. At this age (20 years) and this mileage (200k +), it isn't long for this world as a stock ride.

I know you love this car, so that means its time to do something radical. That means one thing - restore it. Fix it once and for all and be done with it.

pablocruise

Does the car have catalytic converters?

(btw, nice to see you on the forum again)

wilsman

hey im new to this,but ive heard of a fuel pump relay doing this.i wish my 84 looked as good as yours.it will someday i hope.keep trying hope you get it running

CentralCoaster

What's the volt guage reading during this? Almost sounds like it's a bad battery cable connection. With a dead alternator the car would at least run well for awhile after charging.

You should have ~14 volts.



Not true. Pin G feeds through the normally closed side of the fuel pump relay. In other words, it will only read 12 Volts if the relay is off and the pump is being powered by the oil pressure switch. It won't help Jen.

LindenBob

I'm definately no expert on these cars and especially the earlier models but I agree with kize on this. You should check the coil and ignition module. The heat sink compound on the ignition module will get toasted hard over years and no longer can disipate the heat. These things can get really hot and and start breaking down. If nothing else removing the ignition module and having it checked and it is still good then you can chalk it up to routine maintaintence by scrapping the cement hard mastic off and applying a new coat of heat sink compound to get rid of some of that heat. Some useless FYI as I have a terrible habit of tearing things apart to see what makes them tic. The module has some little electronic thingamajiggers inside and is packed with some gooie sticky jell that after months I am still finding stuck to stuff on my work bench There are some hair size wires and a circuit board. Once you see how delicate the internals are you can understand the need of heat displacing mastic. Useless info but might be worthy of a Huh imagine that.

ineVETTEable

[QUOTE=CentralCoaster;1561166105]What's the volt guage reading during this? Almost sounds like it's a bad battery cable connection. With a dead alternator the car would at least run well for awhile after charging.

You should have ~14 volts.




...to a degree. Hard to believe a car that won't idle on 12v + or - would still have enough juice to crank the engine over.

Keystring

Just a thought, But have you checked the ignition switch?(at the bottom of the steering column)

Could be worn enough to cause the symptoms you describe.

golfman2008

It sounds like you have a hand full , Welcome back

imtrumpeter

My vote is for bad ignition module. If it is original with that many miles I would replace it as it will leave you stranded at some point.

Imtrumpeter

TripleBlack88

Had a similar problem several years ago on my '88 and had to replace the computer. Good luck.

jfb

That is right, I didn't look close enough at the circuit diagram. I edited my post.

-=Jeff=-

If all else fails, call Gordon Killibrew. He will literally diagnosis it over the phone.

I think my friend had a similar issue with has 84 and it ened up being some sort of timer module in the dash.. but this was a couple of years ago and my memory on that is foggy

Shawn93PoloConv

You mentioned that the battery has been killed about a hundred times. I had problems with the car dieing. I ended up replacing the battery and the long negative cable. No problems since. The electronics are sensitive to low/bad batteries and Vettes draw a lot of power off of them. It's a cheap fix and probably wouldn't hurt if you haven't changed the battery in a year or two. Good luck and welcome back! Where did your ZR1 go?

Powerdrive

No comment..... way too easy

Sorry.... I've been hangin out in OT too much lately.....

Good luck

CFI-EFI

That is not correct. You are right up until you said "If the engine starts, oil pressure builds up and turns on an oil pressure switch at 4 psi which turns the fuel pump back on." The switch DOES close when the oil pressure exceeds approx 4 psi, and sends power to the pump, but the pump is already powered by the fuel pump relay before that happens. When the engine is turning with the ignition switch in either the "On" or "Start" positions, the ECM receives reference pulses from the distributor and closes the contacts in the fuel pump relay, tunning the pump. When the oil pressure switch closes, it is supplying redundant, back up power, along a parallel path to the fuel pump relay power. Because of the parallel paths of power, the oil pressure switch does NOT act as a low oil pressure shut off switch. The fuel pump relay will continue to power the fuel pump in the case of a loss of oil pressure until the engine quits turning and sending distributor pulses to the ECM. If there is a question as to whether the fuel pump works, 12 volts can be applied to terminal "G" of the ALDL, with the engine off, while one listens to hear if the pump running.

A defective oil pressure switch will NOT cause "the engine to start and then stop when it runs out of fuel pressure due to the fuel pump being off." unless the fuel pump relay is also bad. That makes "If the engine starts and stays running, you have a defective oil pressure switch.", untrue, also, again, unless the fuel pump relay is not working.

I hope that helps to clear up some widely held misconceptions about the C4 fuel pump circuity.

RACE ON!!!

VetteBabe1

Thanks so much for all the helpful suggestions.

The fact that it did this, then quit, then is doing it again kind of helps with the diagnosis. I hope to get Lee to help me work on it tonight, if I can peel him away from his Z06. We are thinking it's ignition module or something of that nature but will try everything as we go!!

I'll report back - and if you can think anything that the intermitency would suggest let me know!

engle1147

Below is the Fuel pump circuit/MAF circuit. The two circuits connect to a degree. A possible culprit for your car's condition could be low voltage on on circuit 998 - which restricts the injectors pulse per second. Good news it's easy to test it!

Test: (Test assumes that car battery is fully charged at 12v! Lower battery voltages may produce lower test results)
Push into the wire with a test probe. With the MAF sensor hooked up the voltage on this wire(the middle wire - dark green)should be 2.5v with the key in the "on" position and a postive jumper wire to term"G" on the ALCL. If less than 2v it's a bad MAF sensor!

Push into the wire with a test probe.With the MAF un-hooked the voltage should read 5 v with the key in the "on" position and a postive jumper wire to term"G" on the ALCL. If less than 5v wire may be grounded/shorted out.