1985 Pontiac Fiero overheating

Yes, overheating can cause the engine to stall along with some very costly damge if it heats up too much. I can think of only 3-things to keep the fan from coming on. The fan itself is bad or the cooling fan switch or there may be a cooling fan relay. The fan switch should be on the radiator. Easiest way I can think of to start the diagnosis is to diconnect the plug from the switch and, using a jumper wire, ground the plug with the key on, engine off. If the fan runs, replace the switch. If not, check the fan. Diconnect the fan plug. There should be 2-pins or slots in the plug. Using a jumper wire, on the plug side going to the fan, ground one side and from the battery jumper the other side. If the fan does not run, replace the fan. If it does run, then there may be a relay in the system that has gone bad. You'd have to find a repair guide to locate that. I don't know where it would be on your car.