Heat related, non over heating issue.

280zxking

New Forum User
Hi all,

I have 1979 280zx, and i have an ongoing issue that has both my mechanic and I stumped. I noticed the issue last year, when driving the car in the morning, evening, or during the winter, it runs like a charm. However, if i have been on the road for awhile, or i start the car on a hot day, it shuts off. Its not a normal shut off as if you switch the ignition, It sputters, sometimes i can keep it going if i keep it revved to about 2500 rpm, but if its idle and hot, then it will start to die. The fuel lite comes on, but its getting fuel, because when i give it gas, sometimes it will rev up, either times it will back fire a little. I have replace the ICU alternator, distributor cap, wires and spark plugs already, the cooling works fine, as the temp gauge shows a normal operating temp. I was thinking it could be the voltage regulator, but im not sure. Any help on what this could be? Feel free to ask more questions about the symptoms.
 

zpuppy

Well-Known Forum User
Maybe fuel heating in the lines, or it could be the air sensor a check of the fault codes on the ecu should prove or not the fault on the air sensor. thats available here on the site (fault codes and how to read em) It does sound to me like over heated fuel however,,(vapor lock)
:)
 

280zxking

New Forum User
thanks! Over heated fuel? thats something, if this in fact the case what are some things i could do to address this issue?
 

260ZG

Club Member
Have you tried changing the fuel pump relay.

I had one that played about causing the engine to die, but re-starting after it had stood for a few minutes.
 

Mr.F

Inactive
The main EFI relay is also a favourite - hidden away in a cavity in the inner wing (alongside the battery on a RHD car). This can kill the engine and then after a period of recovery, allows a normal restart.

If over-fueling then check fuel pressure, change fuel pressure regulator and check to see if cold start injector is staying on.

There is no ECU fault checking facility on a 280ZX ECU...
 

Mr.F

Inactive
To be fair, fuel pump relay failure is not unknown on the 280ZX and would give similar symptoms, so your advice still stands!
 

bigchef

Well-Known Forum User
I had a similar issue many years ago turned out to the black box on the side of the dizzy
 
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