My 4x4 doesnt like to start once it has got quite hot. If I have to stand for a while in traffic for example and I then knock the car off, the car will not start.

I have a feeling its a relay, as when I start the car it will turn over and I will here a click and she fires up. But when the car is hot, then this relay does not click and hence the car does not start.

Anyone have any ideas?