I bought a 1990 780 Bertone 2.3 turbo, for my daughter 2 years ago. We brought it back to life and she's put 20,000 trouble free miles on it (car has155,000 miles total). The only issue has been a random no crank. The car will go months without any issues then, usually after sitting for about 30-60 minutes when the key is turned to start - nothing. The car powers up with the key in the on position but when turned to start nothing happens. I disassembled and cleaned the ignition switch (not the ignition lock) all was fine for 5 months. Then same problem. I replaced the ignition switch next and the starter. All was good for another 5 months. Now she had the same problem again tonight. Starter is good, battery holds 12.9v overnight and terminals are clean. Tried starting in neutral but still no crank. After sitting for an hour the car will fire right up. Got home and the car started 5times in a row no problem. I'll pull the starter relay this weekend, crack it open and have a look inside but if that's not the issue I'm at a dead end, anyone have any ideas?

 

If the starter does not engage - I would test for power ( a simple test light will work) at the solenoid when it does not start. If the car has a starter relay - that certainly could be a problem - if their are other relays exactly like the starter relay - swap them - and see if the problem still occurs.

 

If I could get the problem to manifest itself in the driveway i might have a better chance of finding the cause. But since it's random and occurs months apart and cures itself after sitting for 30 minutes. I'm stuck until the offending part finally dies. I'm hoping someone else has been down this rabbit hole and can point me in the right direction.

 

Just a general thought here. Relays expand with heat and contract with the lack of heat. A relay that may look fine may have a minute crack that shows itself when it heats up and expands. That could explain why it works after waiting a while, the cooling off contracts the solder points and the connection is reestablished.