I have a 89 iroc z28 with the 5.7 tpi. the problem i am having is when i shut the car off i can't start it right up for a couple of minutes. I am getting good spark, 48 lbs to the rail but the pulse to the injector is pulsing but is very dim. I have changed everything i can think of and more to fix this but can't find anything. even had it put on a computer with no luck.
when the car starts it fires right up and runs good but when i shut it off it won't start right back up. Any thing anyone can think of (probably already did it) please let me know.

 

Either the injectors are weak or they are leaking a little. When it won't start, hold the throttle open full without any cranking for a minute. That can help evaporate fuel if its flooded. You could pull a plug to see if its wet (with gas). Another test would be to hook a fuel pressure gage onto the rail and monitor pressure when you turn off the engine. It should hold steady. If not, you have leakage somewhere. The other possibility is that the injectors are weak and not shooting gas in. If a shot of starting fluid through the throttle body starts it right up, you are suffering from lack of fuel.

 

It's a TPI not a carburator, fuel is in the rail.

He has 48 PSI steady to the rails.


Again, he has 48 PSI steady to the rails and it starts normally after two minutes.

 

The 48 pounds steady you mention. Is that with the car running or not? I am talking about if it holds pressure with the car off. If the injectors leak slightly, you can get a flooded engine condition. That shows up as a pressure reduction. I am not sure what the time limits are but if you start losing pressure as soon as the car is turned off, that may mean injectors are leaking into the engine. This would prevent the car from starting right away. The excess gas must be swept away before it will start.

 

The gage does not go to zero it takes about five min to drop to 7 psi and stays there so i don't think its a leaking injector.

 

Using a test light? Is it always dim, or only when the car wont start

 

I did a search on fuel injector leakage and this is one of the best that I found. From what you said, pressure going to 7psi in five minutes does not look good. I would say at least something is leaking.

https://www.thirdgen.org/techbb2/sho...jector+leakage

 

i was using a noid light from snap on. Not some **** tool from my box And yes its only when the car won't start. When it starts the light is very bright and pulces good.



I think the problem lies somewhere between the ecm and the wiring harness for the injectors. Does anyone know what runs the power from the ecm to the harness for the injectors. Tried replacing the ecm and did nothing to help. Thats why i think its the wiring.

 

Something like this maybe?

 

oops

 

try this again.

 

Your engine is wired with two separate banks of four injectors. The only wiring common to all 8 injectors is the ignition switch and the ECM ground connection (labeled ENGINE GROUND on the schematic).

 

The following goes with the schematic in my last post. Hope you can read it.

 

pt 2

 

Good ol' systematic troubleshooting.......

 

thanks hope thats the problem