Hi folks I have a 91 audi 80 quattro. The car runs great untill it gets hot. The car is not overheating the temp guage is barely in the middle, It gives no warning just turns off. When it is acting up I have spark and fuel pressure, but the car will not restart untill it cools off a bit. Once it has had time to cool down it will run fine untill it reaches its "shut off point". It's driving me crazy!!!! I have replaced coolant temp sensor,fuel filter, full tune up etc.... Anybody out there have any ideas?

 

I suspect the fuel pump is the problem. When they heat up the loose contact internally. On my car the pump would only fail when the fuel level was below half. It seemed a low fuel level reduced the fuel's cooling ability and the pump would quit, stranding me in some very inconvenient places.