My cousin has a 97Z that is stock besides exhaust and cold air intake. He has a problem starting it after driving it. If it sits all night, fires up with no problem everytime. During the day, even after sitting for 8 hours it will take 3-5 seconds to start. Any ideas?

 

Same issue here but I haven't figured out my problem yet. I still need to check my fuel pressure though and see if maybe the pump is losing pressure or for leaking injectors. It was either those two things or possibly the coolant temp sensor.

That is the advice I got from some of the members here though.

 

If you think about it, sitting longer lets it start easier. It could not be a leaking fuel pump check valve allowing the fuel to drain back toward the tank. The same with a leaky injector or a leaking FPR.

The problem gets better the longer it sits. So to prove (or disprove) my theory open the gas filler cap every time he parks it.

He could also disconnect the vent valve behind the driver rear wheel and try it a few days with it disconnected. However that could throw an evap code.

It sounds like it has a restriction and is not letting the air into the tank as fast as it should. After sitting long enough the air eventually gets in and the vacuum is released.

 

I had start symptoms like what you are describing. Turned out to be the fuel pressure regulator (ruptured diaphragm). It's a simple check. Pull the vacuum line off and check for any sign of fuel. Line should be dry.

 

Well?????

 

I will update when I hear back from him.

 

I tried removing the gas cap and it seemed to help. I also notice the cooler the temperature the better.