So, this is my first time driving my '78 Z on a regular basis in such hot weather. A recent heat wave has brought temperatures well into the 90s. Here's the problem: When I go to start it (cold engine), it runs fine. But when I park and return to start it within 20 or 30 minutes (engine still hot), it doesn't start. It takes a long time to finally get it running, and once I do it runs great. I'm aware that vapor lock is non-existent with EFI, so are there any other diagnoses? Does it have to do with the heat or is that just a coincidence?

Mine started doing the similar thing at the end of last summer/fall season before I put it away for winter storage and I haven't had a chance yet to correct it. My guesses so far that I'm thinking off the top of my head is either

A) Faulty Coolant Temp Sensor or

possibly I got a bad check valve in the fuel pump and it's not maintaining 36.3 fuel pressure like it's suppose to which is causing the "Hard to restart" issue. If I shut mine down and restart it right away it fires up instantly. It only struggles to start after sitting for a period of time so I'm kinda leaning towards B. I'm not sure yet. I got to do some testing myself

Edited April 21, 200917 yr by DatsunZsRule

I concur with solution B. If it was solution A, it wouldn't run right once warm but it would start.

yeah thats my thought as well. Looks like mtndude isn't too far from you stephen ( San Bernardino, CA)

We've corresponded. He's just up the hill 20 minutes or so from me.

Wow that is close. Cool.