chs1974

I have an 87 Corvette. After getting a no start situation I took it to my mechanic and he replaced the fuel pump. The car ran fine for two days or so and then in the morning no start, car cranks over fine but no start. I had the car towed to my mechanic again and he got it running again. He said it might be a fuel pump sending unit. He did not replace it and gave the car back to me. The car ran fine for 3 days or so and then two days ago a no start situation. So today after 2 days I started my car to my amazement. I saw the security light come on and then it went off. After about 10 minutes of running the car I shut the car off. I went to my car after about 30 minutes or so and I got a no start situation again. My security light is not on this time.... Any help would be greatly appreciated...!!!!!

Frizlefrak

A no start or a no crank? If VATS is at fault, it won't crank at all.

As I said in your other thread, you don't have a mechanic, or it would already be running correctly. You have someone guessing at the problem on your nickel. Is this "mechanic" in Rancho Cucamonga by any chance??

chs1974

It cranks over, but doesnt start... where should I look for then... I already replaced the fuel pump. I know its not the igntion because it does run. any ideas???

vetteoz

Either no fuel or the injectors not being pulsed.
Pull the codes
http://www.corvettephotographs.com/c4vettes/codes.htm

If you have a code# 46 showing ,the computer is not getting the fuel enable signal from the VATS module.
VATS has two functions; fuel and starter
http://www.thirdgen.org/vats_passkey_system

If no codes put a noid light on the injectors and see if they a being pulsed.
If they are, you have a fuel problem , if they aren't then the computer is not pulsing the injectors.
If it starts cold but not hot ,possibly the ICM in the dist is going faulty with heat and not supplying the
dist ref signal to the computer so it knows to fire the injectors

but have you checked the actual fuel pressure at the fuel rails?

yd328

Before you can start picking a system you have to make some basic checks first and go from there. You should check for spark, check for fuel pressure, and check for injector pulse with a noid light. You can also see if there are any trouble codes present in the ecm. These checks and what has been posted will help point toward the system that is giving you trouble.

Gary

chs1974

Thanks Gary. I will check for codes. I know I had a code 33 Maf sensor, which sometimes triggers my check engine light, but not all the time. I dont have a noid light, but will ask around. Also I noticed in the past that sometimes my key would not go in the lock cylinder, but after a minute or so it would slide right in. What would cause my key from not entering for a few seconds?? Im not worried about spark, because I dont think thats the problem because my car started right away. I believe I have a fuel problem or vats problem

Cliff Harris

As Frizlefrak said, you don't have a mechanic. You have a "parts replacer". He obviously isn't fixing your problem or you wouldn't be posting here.

Error code 33 doesn't necessarily mean the MAF is bad. It could be the wiring or a bad connection. It sounds from the "but not all the time" that you have an intermittent connection.

This is what a noid light looks like:


You remove an injector connector and plug this guy into the connector. Then crank/run the engine and see if the LED flashes.

Dans 85

Sometimes I wonder who's running who in circles.

chs1974

The car started twice after the fuel pump was installed, but then I would get a no start situation 2 days later. Then it would start again after 3 days or so the second time, thats what makes me believe its not an ignition problem. I ran the engine to operating temp and then shut off.

Frizlefrak

It wasn't a fuel pump problem either....or your "mechanic" did that wrong too.

One more time....HOW MANY LBS OF FUEL PRESSURE DO YOU HAVE DURING A NO START EVENT??? Test, don't guess.

I can type it larger if that will help.

chs1974

Ok I will have to get a fuel pressure tester and I will post it here. Thanks for your help... Yeah my mechanic is on the "shady" side, I think this is beyond his expertise...I just dont want to spend a whole lot of cash to fix it, and I hope that this forum can help me get to the bottom of this problem...

Frizlefrak

If diagnosing a no-start on a 26 year old car is beyond his expertise, perhaps he should seek a change of occupation. I'd hate to see him try to trace an open circuit to a body control module.

Anyhow, post your fuel pressure during a no-start event. If it's below about 38-44 psi or falls off immediately, we just narrowed the problem considerably. If fuel pressure is fine, then we find out what else isn't. They only need 3 things to run.

1. Correct mixture of fuel and air.
2. Suitable compression.
3. Sufficiently strong spark delivered at the correct time.

If those three conditions are met, they run. If one or more is missing or deficient, they either don't run correctly or at all. Narrow down where the problem lies, and correct it.

JrRifleCoach

IMO the VATS is not reading your key's resistor button all the time.
Do you have another key to try?