I am asking for a mechanic friend of mine, he owns a Porsche garage for over 40 years.


Car is 1991 964 turbo. Car starts normal when cold. But after driven a while, engine warmed up, parked it for 1-2 hours, the car cannot be started (just cranking). Leave the car for another half hour or an hour, when engine is sufficiently cooled, it starts normally again.

Checked for a fuel pressure, normal. Exhaust CO, normal. No leak.

Any guesses/suggestions why car is behaving this way?

Thank you for your help!

 

Two things come to mind. One is electrical and one is fuel related. Our cars are typically subject to heat soak after use. This can cause problems with spark or fuel supply. Check for spark when car is hot. Also check for vapor lock in fuel supply. Fuel pressure can appear normal but vapor lock can prevent fuel delivery. Good luck.

 

I would also check fuel relay. As weird as it sounds this thing always acts up, does it on my 993.