ATX won't start after it gets warm... any idea?

[Trojan Man]

A friend of mine has a 95 ATX. After he drives around for about 20 minutes and shuts the car off it wil not start back up. It will fire really quick but won't run.

I've found that when this happens, the fuel pump doesn't prime when you turn the key. However it does come on if you ground the test pin. If you wait about an hour or two it will start up and run for a while then quit again.

When cranking it the tach does move, so I'm not thinking it's a CPS. He also told me that while driving it hard today it sputtered like it wasn't getting fuel.

All this leads me to believe it's the fuel pump but I don't see why it would be heat related. And also he just went back out to try starting it again, the fuel pump primed when he turned the key but it still won't start.

Any ideas?

 

[projectSHO89]

Try grounding the FP lead before starting it (heck, leave it grounded as a test).

Sounds like the FP relay in the CCRM is flakey and is not supplying power to the pump constantly.

Only a fuel pressure guage will tell you for certain if pressure is lacking.

A voltmeter or test lamp can be used to check the output of the CCRM pin 5. I posted a couple weeks ago on a procedure to test the FP electrical system. It's not bookmarked on my computer, but should be easy for you to find using the SEARCH feature.

Steve

 

[AutoSHO]

As an addition, the reason it might be the fuel pump quitting when its hot is because the fuel pump "warms up" as does any mechanical item when in use. If the friction in the pump is too great the car wont start due to lack of pressure.

I would do like Steve said and ground it before trying to start. If that fixes it, try priming the pump 2-3 times before starting.

And to top it all off: If you have good fuel pressure and everything else checks out, the MAP/Baro sensor caused a very similar problem on my car.

 

[Trojan Man]

It turned out that it was the fuel pump. Just figured I'd let ya'll know.