QuestionThe car will run approximately 10-12 minutes until it reaches temperature. The fan will come on and run about 15-30 seconds and stop. Shortly after that the engine quits and will not restart. I have replaced the thermostat, fan relay, coolant temperature sending unit, and engine coolant temperature sensor, fuel pressure regulator, fuel pump relay, idle air control valve, oil sending unit, ECM, cam sensor, coil and module. There are not any error codes.
I pulled the fan, hooked it up direct and let it run for 5-10 minutes. It ran cool, no bearing noise or excessive play. I assumed it to be good, so I reinstalled it. I put two household fans in front of the grill and the car ran for close to 30 minutes before it quit. Also installed a rebuilt ECM and it did the exact same thing. So I reinstalled the old one.
Checked the fuel pump (30-31 lbs. constant pressure) and the injectors, everything is fine. Cleaned the MAF sensor and even replaced it and still have the same problems. There aren't any air or vacuum leaks. Disconnected the battery to clear the computer, took it for a ride to re-teach the computer as per the repair manual, and it quit running after 10 minutes.
After disconnecting the MAF sensor and restarting the car it ran for 30 minutes before I shut it off. It didn't run the best, but it kept running. The car did not stall. The fan cycled on and off like it should. The engine didn't get excessively hot.
When the car stalls I can spray starting fluid into the air filter and it will attempt to start. Tomorrow I’m replacing the throttle position sensor.
What else could the problem be?
AnswerHi Sharon,
You need two things to run.
A good spark. And the proper air fuel mix.
I assume you have checked for presence of a good spark, and spraying the starting fluid indicates there seems to be spark.
You checked the fuel pressure, but did you have it connected when the engine dies? The pressure should stay up there till AFTER the engine dies.
Assuming the pressure is staying up, and the spark is still present, I would want to use a few "NOID" lights to see if there is injector pulses when the engine dies.
Where I am going is, if there is fuel pressure, and injector pulses, and good spark...then I would check the vacuum.
It is remotely possible that the EGR valve is opening, which would just kill the vacuum.
Another thought is the exhaust system plugging up, due to rust flakes covering all the holes, but that is quite far fetched. I have seen it in trucks with screens in the tailpipe, but they would loose power first, and would struggle to run, and you could hear the pressure building in the exhaust, so I doubt that is your problem.
I might be inclined to unhook the EGR valve and see what happens.
You say it isn't getting hot, but have you considered the water pump? When the thermostat was out is a great time to check for coolant flow.
But if the ECM shut it down for overheating, I would certainly expect a code to be stored.
See what that vacuum does just before it dies.
Van
