My 280z won't start every time in the mornings for some reason. The car used to be a daily driver but know I only use it on weekends .i'd tried to take it to work some days but it wouldn't start. by the way I start work at 2:30am so it's a little cold. The funny thing is that if I try to turn it on after 12:30 am when the sun is full the car turns like a champ. I'm confused does the car have it's working hours;)

Cold start valve perhaps?

Or perhaps your car is trying to get you to move to the day shift

I'm assuming it's turning over just won't fire up? Will it start if you give it a little throttle when turning over? Do you smell gas after you turn it for a while trying to get it started? Might be a broken cold start valve but I'd let other put there input in before buying anything.

That's what I'm thinking , may be the coldstart.and before I used to drive it all the time it may be it's way of telling me to drive it more often

It will turn over, but just won't start even if I give it gas. The first two or three turns of keys the car starts but shuts off right away. If I keep on doing it I eventually drain the battery

It will turn over, but just won't start even if I give it gas. The first two or three turns of keys the car starts but shuts off right away. If I keep on doing it I eventually drain the battery

If the car starts but then dies, it could be the fuel pump safety cutoff. On the 78 I believe it is controlled through an oil pressure switch. The switch has to see oil pressure to close the contact to run the fuel pump. Typically (at least for 76 with the AFM switch) the car will start, run for ~3-5 seconds, then die. Not sure why warmer would be better than cold, but it is something to look at.

If this is the problem, then hitting Start real quick as it is dying, will get it to run a few more seconds again (because Start bypasses the switch), although you will get a grind from the starter gears.

I had this problem on my 76 which has the AFM controlled fuel pump switch.