Grahamski

I have a 1995 camaro. 5.7l
6 speed
EFI

The issue i am having is the motor will start when it is cold and run Great (I'll run it for about a hour) . BUT, when i turn the car off leave it for 10mins. I'll try and start it but it takes forever and a day to get it to run again. My check engine light will come on but the car will run fine.

Why am I having this issue?
I have replaced the starter, battery, alternator, fuel filter, spark plugs, and the air filter.
I haven't noticed any fuel leaks from the gas tank or around any of the fuel lines.


Thank you

Grahamski

mrmint69

Check for codes and see if it leads to anything. Have you checked the fuel pressure when its doing it? Several things will have problems after getting hot, that don't do it when cold.

shoebox

Why ignore the check engine light and start replacing stuff? The light is there to help you diagnose. Use it.

Grahamski

So I have tried using 2 code reads and 2 scan tools and they won't read. I have purchased a fuel pressure gauge and I am going to attack the issue see what readings I get. What kind of pressure am I looking for?

Injuneer

For a 95, you need an OBD-I scan tool, with a 12-pin to 16-pin adapter plug, or you have to use jumper wires as Shoebox shows on his website. You have an OBD-I PCM, and an OBD-II style 16-pin ALDL connector, which makes it difficualt to scan. You also cannot use the $30 Actron scanner that short the ALDL connector pins and flashes the codes on the SES light. 1993 was the last year that worked on an LT1:

http://shbox.com/1/xraycable.jpg

Newer OBD-I/OBD-II scanners may not work if they are powered by 12V off the ALDL connector. There is no 12V pin in the GM OBD-I ALDL connector.

Fuel pressure checks:

Check for excessive leakdown - turn the key to prime the fuel pump without starting the engine. Pressure should rise to at least 40psi by the time the pump shuts off. The pressure should then hold, or drop very slowly. It the pressure drops rapidly, you may have a problem with 1) a leaky check valve in the fuel pump; 2) a leaking injector or injectors; 3) a faulty fuel pressure regulator; or 4) leaking fuel lines, including the pump discharge lin internal to the fuel tank.

Check pressure at idle - start engine, let it idle. Remove the vacuum compensation line from the fuel pressure regulator, plugging the end of the vacuum line to prevent a vacuum leak. Fuel pressure should be 43.5psi, with GM spec accepting anything from 41-47psi.

Reattach the vacuum line to the fuel pressure regulator. Pressure should drop proportional to intake manifold vacuum. A drop of 8-10psi from the "no vacuum" pressure is normal for a stock cam. A smaller drop would be seen with a more aggressive cam.

Check for ability to meet max fuel demand - tape the fuel pressure gauge to the windshield, take the car out on the road and at WOT, above 5,000 RPM the pressure should stay at 40psi or higher.

As you drive and move the throttle, it is normal for the pressure to move around, in response to changes in manifold absolut pressure (MAP).