I need some help I have a 91 camaro z28 5.7L 350 and it will not crank up for about a hour after it has been driven. the fuel pump and ecm has been changed. Can anyone offer some advice.

 

No crank or starter click? With the key on does the security light stay on? If i had to take a wild guess id say its related to VATs. Vehicle Anti-Theft System.

My car used to do it randomly, it'd be fine then id park it somewhere and it wouldn't crank and sometimes it would 20 mins later or sometimes a day later.

 

Or it's a heat soaked solenoid.
Read over this tech article.
https://www.thirdgen.org/solenoid

 

the engine turns over but it will not fire up ofr about a hour

 

Before you start replacing starters or steering columns, you need to answer two important questions:
- do you have spark?
- what's the fuel pressure?

Lou

 

the fuel pressure is 42 psi and yes it has a sprak

 

Alright.
Spray some carb cleaner down the intake. If it starts, you have a fuel delivery problem.
It will die afterwards, of course.

You can also turn the key on and ground the blue (or green) wire on an injector for a second. Try staring again. If it starts, the injectors are good.

Check the connectors and wires on the back of the distributor and top of the coil. If the ECM doesn't see any pulses from the tach/coil, it won't inject any fuel.

Let us know.
Lou

 

After the car has been driven and i try to start it again but it will not crank. The fuel pressure is 45 psi at all time and it sparks everytime but the no injector spray. The fuel pump, the fuel filter, ecm chip, distributor cap, distributor rotor, the spark plugs have all been changed. checked the timing. But the injector will not spary any fuel.

 

Here you said that it turns over (aka crank) but today you say it won't crank. That's creating confusion.
The verb "crank" means that the starter is turning the engine. It comes from the old ages when cars had crank handles and the driver had to manually crank the car up.

So we need to make sure that we understand what's going on here.
Does the engine crank (starter turning it)?
Does it fire up (run) at all?

Lou

 

It will turn on fine and run good for about a hour but then it shut off and will not turn back on

 

Ok, you need to be clear here.

Youre driving around, car shuts off. Thats clear.

When you go to restart, does the motor spin? Yes or no.

If no, check the starter solenoid.

If yes, that determines that the engine "cranks" and doesnt "restart."

How did you check fuel and spark? Mine had this same problem and what was happening is the coilpack was getting hot and shut off. I grab the coil and its like, smoking hot. I put a replacement coil in and the car started right up.

 

I think he means it won't restart after he shuts the car off.. it's kind of unclear though.. If I'm reading this correctly he can start and drive the car, shut it off, and it won't restart. It will however crank. So it cranks and doesn't start, he has fuel pressure but the injectors arn't firing, he does have spark when this is happening.. that is if I'm reading this correctly.. do I have that right?

 

correct i can start it, drive it, and turn it off but it won't restart. i have 45 psi fuel pressure and i have spark everytime but the injectors are not spraying

 

Alright, it's clear now.

Did you try grounding the blue (or green) wire on the injectors? Did it fire up for a sec?

What does the security indicator do when you turn the key on on restart?

Can you swap ECMs with a friend?

Lou

 

yea going to get a new one and thank u for all them help

 

That is definately strange. Most times when our cars lose injector pulse they dont have spark due to the module in the distributor. My next stop would be the ECU.

 

replace the starter.

10-1, that's your problem. what happens, is when the starter sylenoid gets hot, it doesn't work. that's why you have to wait an hour or so.. so it can cool down. then it fires up again.

had this issue many times. replace the starter.

 

that makes absoluetely no sense since the starter is working flawlessly. It cranks, has spark, but no injector pulse, putting another starter on it isn't going to pulse the injectors. Have you read this thread at all?

 

Ive read it and im still confused.

by turning over you mean it cranks but doesnt turn on? that should take care of the starter being bad.