Engine Performance problem
1990 Ford F150 6 cyl Two Wheel Drive Automatic 176, 00 miles
I'm an experienced shade tree mechanic for over 33 years but this one has me stummped. My strait 6 engine which I bought runnig bad, would at times run 100% and very strong after a difficult time starting. I have filled both tanks to full, one was already full. It seemed to run better when it was warmed up. But then it was like ssomeone pushed a button and it would start running lousy with a intermitting miss. Then, it would happen again, start running 100% and strong. The next time I tried to start it it back fired and blew off the muffler. Yeoww!
Then, I couldn't start it no matter what I tried, even after spaying stater spray in the intake. Here is what I have done to try to find the problem. I checked the fuel line pressure, good. Checked both pumps independently - running and pressure good. Checked for codes - no codes (very frustrating) replaced the MAP sensor. Replaced the water temp sensor. Replaced the Fuel pressure regulator valve. Took the timing cover off and checked the timing gears and timing - O.K. Like new. Replaced the ICM module on the distributor. Then replaced the distributor pickup module and rotor inside the distributor. Replaced the rotor and cap, sparkplug wires & spark plugs. I get a strog spark. Did compression check about 145 on all cylinders. Replaced the coil. Checked the injectors for clogging all clear and spraying. Replaced the fuel filter. Checked the mechanical timing again all good. Replaced the idel speed control valve. Video taped with the valve cover off and spark pulg wire on a spark plug for number one, then slowed the video down on my computer to wath the timing while cranking. The timing and spark to valve action is perfect. Next I pulled the injector rack off, zipped the injectors tight to the rail and video taped the cranking sequence. At first I get 8 all injector shots every 1/2 second while cranking, but then it injects right when the exhast valve starts to inguage. Ah Hah - this is out of sequence right. Could this be my problem? What controls the injector pulse since there is no crank or cam position sensor on this model? See I've got everything that says this truck should run - but nothing! Help!
have the same problem?
Saturday, October 11th, 2008 AT 10:53 AM