Warm starting problem

[actros]

Looking for advice please , I have a 1991 5 litre TPI trans- am this car starts first turn of the key from cold and runs fantastic, but today I have found when you turn it off after getting to running temp one of 2 problems occur . Either you turn the key and all the ign lights come on as they should , but wont turn over , theres no clicking sounds and the car wont turn over for about ten mins, but the battery is fully charged, and no loose wires anywhere. The other problem that sometimes happens is the car turns over very well , but does not fire up, but yet again leave it ten mins , then it does any ideas please.

[cptsideways]

water temp sender, the one the ecu sees not the gauge one is faulty

[Mr2Mike]

Possibly a fault ignition switch causing both issue - or maybe it's two separate issues.

It's not unknown for faulty starter motors to stop working when they get hot, my old Astra suffered exactly this problem. Coolant temperature sensor can cause hot or cold starting issues as well as the Captain says(but won't stop the starter turning the engine over). Crank position sensors are also very prone to temperature sensitive failures.

[HowlerMonkey]

Any sensor that is fed a reference voltage can cause this if the sensor is bad.

[actros]

Thanks guys for your advice.

[megamaniac]

Try putting a jump lead from the battery earth to somewhere on the engine/gearbox casing .If it cures the problem change the earth on the battery to g/box.