If the engine isn't overheating you should not be wasting your time and money on anything to do with the cooling system, meaning the radiator and fan. You would have had the car repaired for a lot less money if you had involved a mechanic who would have properly diagnosed the problem. In this case what you've described is real common on any car with electronic fuel injection.
Since you have an engine running problem but didn't bother to list the engine size that you have, I can offer only general observations. Most engines use a crankshaft position sensor and a camshaft position sensor. Both commonly fail by becoming heat-sensitive. That means they fail when they reach a certain temperature, then work again when they cool down. The most common complaint is the engine runs fine for any length of time, but once it is stopped it will not restart a few minutes later. That's because of "hot soak", a condition where there's no natural air flow to cool the sensors and engine heat migrates up to them causing them to fail. The second most common complaint is the running engine stalls after a specific length of time which equates to reaching a certain temperature.
The first thing you have to do to diagnose this is to find out what is missing when it won't restart. That will be spark, fuel, or both. First check if you have spark. If you do, you have a fuel supply problem. That is not common but I'd first suspect a plugged pickup screen on the fuel pump assembly. If spark is missing, measure the voltage on the positive terminal of the ignition coil. If your engine has a coil for each cylinder, you can measure on any one of them. The positive wire will be the one that is the same color at every coil and every fuel injector. You should see 12 volts there for one second after turning on the ignition switch. What is important is if that voltage comes back during engine rotation, (cranking, in this case). If it does not, the next thing to do is read the diagnostic fault codes. There may be one set for either of those two sensors I mentioned. It's important to understand that fault codes never say to replace parts or that they're defective. They only list the circuit or system that needs further diagnosis. In this case however, it's a good bet the sensor is the cause of the intermittent stalling.
When either sensor stops sending a signal, the Engine Computer turns off the automatic shutdown (ASD) relay. That removes power to the ignition coil(s), fuel injectors, and fuel pump or pump relay. You can try swapping the ASD relay with one of the other ones like it so you don't overlook something simple, but they really don't fail that often.
Friday, August 23rd, 2013 AT 2:08 PM