I own a 1999 Jeep Grand Cherokee. About 4 weeks ago I went out to get into the car to drive it and it would not start. It would crank but the engine would not turn over. I had it towed to a Jeep dealership and they called me back to tell me that I had no fuel pressure and suggested replacing the fuel pump. They did that and I drove the Jeep home and it drove perfectly for the next 3 weeks. Went out to start it and same thing exactly as before, would crank but the engine would not start. I had it towed again back to the Jeep dealership and they called me to tell me that the problem was that the PCM was not providing power to the ASD relay to turn on the fuel pump. I questioned them about why they had originally told me that it was the fuel pump since I suspected that the problem the first time was the PCM and they had just misdiagnosed it. They insist that it is a different problem and the two are not related and that a failure of the PCM would not cause no fuel pressure. Can anyone give me more information or opinion as to whether in fact the PCM failure could cause there to be no fuel pressure? Also, I forgot to say that both times that the car would not start we used the key method ourselves to try to get a trouble code and it would not work either the first time or this last time. Thank you for your time and help. :confused:
10-04-2013 02:16 PM
I am trying to solve my no fuel pressure at the rail. From reading your post I would ask this question. If the dealer said the PCM was not providing power to the ASD relay to turn on the fuel pump, then how would you expect fuel pressure? If the fuel pump will not turn on then it can not create fuel pressure. I would say the dealer is just throwing parts at the problem and the tech does not really know how to diagnose the problem. It is possible that the PCM going bad is coincidental since she ran for a few weeks. I would get a second opinion from a shop that works on Jeeps.
10-04-2013 02:39 PM
Im a Technician so I now I can help you out with this problem. From looking at the wiring diagram its easy enough to pin-point the issue. The first thing I would need you to do tho is be able to verify if you are getting fuel pressure, you don't need to crank the engine to build pressure, as soon as the ignition is in the "ON" position it will activate the fuel pump relay. If the dealer just replaced the fuel pump and it is a crank-no-start condition then I can take a shot in the dark and say that it is probably a bad fuel pump relay. Let me know more about the issue.
10-04-2013 07:10 PM
Jump the relay to make sure its not a pcm issue. 30 to 87