Any ideas on why a 1999 Ford Taurus with 66,000 miles would start and immediately stall after drives over 45 minutes? Starts fine in the morning and or after sitting for hours. Can’t drive anywhere and expect to get back! Following have been checked and or replaced and the condition continues: battery, starter, ignition coil & spark plugs. No diagnostic codes appear when the car is dead. Usually when the mechanic goes to work on it it starts fine, have to drive it or keep it running to get it to die. No engine lights, no clue. My mechanic is usually good but this has been going on for over a month and he has no clue.
One thing that can cause this is a defective Crank Shaft Position sensor. These sensors can heat up where the computer see’s no crank shaft rotation so there’s no spark or fuel injection. Once the sensor cools back down it functions again.
Have your mechanic check the resistance of the sensor while under ambient temperature, and then check the resistance while heated up with a heat gun. This will require removal of the sensor.
Tester
It could be a failing fuel pump also. The best way is to have it dead at their shop before the 45 minutes is up, and work with them so if it happens they look at it right away. We played the same game with an 03 windstar, more intermittent than yours, and had the fuel pump diagnosed and replaced upon my instructions to the wife to stop by the dealer turn it off, and see if it would start every time she passed by, or wait the 45 minutes if it would not start. It had been towed twice and no problem found as it started right up by the time it got there. Third time no start I gave it an hour then all was good. Then after a couple of weeks it failed to start at the dealer and they figured out the problem. That was under the extended warranty so it was nice to have no cost repair and it has been fine for 2 years now.
My 1997 had similar behavior when the Idle Air Control valve started going bad - I could run all day in that car with no problem. It would start just fine in the morning, or if it sat for 30+ minutes after a run. But go for a moderate length trip, stop, and then try to restart after just a few minutes, it would catch and start, but struggle like made to maintain an idle. Punching the gas and taking the rpms up to 2000 or so would keep it from stalling, and I could usually let off the gas after a few seconds and things would be fine.
When I took off the IAC, mine was all gummed up, and it was probably temp-sensitive behavior since it was junked up and sat on top of the hot aluminum manifold. When I cleaned it, the behavior improved significantly, but it did not eliminate it completely. When I replaced it, things went back to normal, and I’ve had no problems at all in the 3+ years since.
Thanks, that is one of the things they have tried. Problem persisted. They tried a new sensor.
Thanks, that’s what they thought at first. Now they don’t. I have made sure that it dies on the spot for them but even that has not helped the situation. Each time I had towed there it would start right up for them! Now I just leave whereever it dies and go back the next day and start it. Very frustrating.
It seems it might haved been the crank shaft position sensor after all. They changed it as well as a CAM sensor and drove it/kept it running and it was starting for them. I will remain skeptical until I drive it a good distance and then get it to start again!
Thanks for your help!