'78 280Z has trouble starting in hot weather

[mtndude]

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?

[DatsunZsRule]

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, 2009 by DatsunZsRule

[sblake01]

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

[DatsunZsRule]

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

[sblake01]

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

[DatsunZsRule]

Wow that is close. Cool.