95 F150, Cranks but no start.
This makes no sense to me. When the truck decides not to start, the Check Engine light stays on while cranking. If it decides to start, the light goes off during crank. Various thing have fixed the problem, but not allway. When this first happened, I checked the plugs, they were dry. Ah, a fuel problem, I thought. When the tow truck arrived, the driver checked for a spark, NO Spark!. evidentely, if one doesn't work, the computer prevents the other from working. Anyway. The ECM was changed, and all was fine. a week later the check engine light came on. The system was analized and found that the wrong ECM was installed. The original one was put back and the truck ran ok. 2 weeks later, it won't start. Another tow truck driver say's that he knows Fords, and presses the schrader valve on the fuel line. Truck starts on teh first attempt. This happens again, so I tried the schrader valve. Doesn't work this time. Called a Tow truck. We pushed the truck out of the garage. Just before towing, I tried the engine again. It started with the first attempt. left it at the Ford Dealer for 2 days. They tried starting it many times. It started on every attempt. Next time it happend arrange for the Ford dealer to make a house call. While it was cranking they checked fuel pressure, it was normal. They check for a spark, there was no spark, they installed a known good coil, still no spark. They left to get some other equipment. While they were gone, i managed to get it started by fiddling with the Overdrive control in the engine compartment. It would fire one time then stop. I repeated this operation several times until the engine continued to run. But when I closed the hood, the engine quit. I opened the hood and started the engine again. When I closed the hood again, it stopped. next time, it kept running. Last week, when it wouldn't start, I tried the schrader valve again. Engine started with the next crank. Following day, at lunch time, it wouldn't start. 2 hours later it started at the first attempt. I hadn't even touched anything. At 5pm, it wouldn't start. a minute later, after leeving the ignition switch turned ON for a few seconds, it started right up. The following morning, same problem, this time nothing fixed it. So, this morning, I decided to do a bit by bit close inspection of every component. First, I tried startin it. It didn't start. I opened the hood, but before touching anything, I gave it one more attempt. IT STARTED WITH THE FIRST CRANK!. There is nothing being touched by teh hood hinges. The only common denominator in all of this is the ignition switch. It is used every time. So, I will buy a replacment and hope that works. Anyway, to my question. Does anyone know if there is a seperate circuit in the ignition switch dedicated to the ECM? If all this doesn't work, does anyone know if priests will exorcize demons from an F150???