Hard Starting, but runs fine after finally starting

[carterlrae]

So what turned out to be the problem "dzman1331"? I have the same problem with the same symptoms. I've got a 73 240z. Hopefully, you got it fixed, so I can start where you finished. Thanks.

[eatingZ]

hey all,

i have had my 77' 280 on the road for a few weeks now. almost 3,000 new miles on it's odo, bringing it to 44,444 original miles today!

anyway, the car starts and runs great 95% of the time, once or twice i have noticed a small increase in the revs at idle after starting, normal idle around 800, little blurps bringing it around 1,100 and bouncing round a bit around there. after driving it comes back to 800 at a stop light or parking spot and stays there very steadily.

the other issue, is when turning the car off after coming in from the highway, or even after some city driving. very seldomly, when i go to turn the car back on 10 or 20 minutes later, it coughs and stutters, starts and dies, starts and dies. it takes a few tries or even 5 to 6 tries and seems to be firing on only a few cylinders. in these instances, it never quite feels like it gets running as usual, i then pull off and drive and then it will act as usual and drive on all cylinders or get full fuel...

if i stop and idle, even 20 or 30 yards later, it is idling fine as usual, 800, no burps or stutters.

like i said, i've been on the road for the last few weeks, and it has maybe done this 6 or 7 times total. i am probably starting the car 10 times a day if not 20.

just want to keep ahead of any issues, looking for some investigative direction.

thank you all for so much experience and advice.

[FastWoman]

It's a common, and somewhat mysterious, issue with the EFI Z. Do a search for "hot restart," and you should find more than enough speculation. In fact there's a new thread by Zed Head, in which he suggests it might be the coolant temp circuit that overheats when sitting there, causing a lean running condition. Many have speculated the problem is from fuel vaporization in the hot injectors. (Fresh fuel is then required to cool them.) Some say it's vaporization in the fuel rail, somewhat like a vapor lock condition in a carb'ed engine, but that theory is vigorously disputed and probably without too much merit. The short story is that we don't really know, even after roughly 35 years.