Hey guys, sorry for the long post. I have an 02 F550 7.3 that cranks but will not start. We'll most of the time it won't start. A little history on the truck. I bought the truck knowing that I would probably have to put some work into it. About 2 weeks after I got it. I was wiring up a brake controller, It died and wouldn't start. I believe that i bumped the wire that goes.from thr chip to the switch. No communication with the scanner( OTC Genisys) lead me to believe that the ecm was bad. Got a new one and it started, the tach and trans temp guage did not work. Drove it about 6 months and had a few issues with it, but nothing too serious. I did have an issue with it losing power to the point that it wouldn't hardly move itself. It took me a while to figure out that the fuel tank liner has failed. In the meantime, I had replaced the icp, ipr, valve cover gaskets and harnesses. 2hen doing the valve cover gaskets, I found that the engine wiring harness had a bunch of bare wires so I replaced that as well. So after replacing the fuel tank and sending unit, it ran good. I put the chip back in the ecm and the tach and trans temp guage started working again. The day after Christmas, I was headed home with the it and it lost all engine power and died. Towed it home and could only get about 300psi out of the hpop. I replaced the hpop and the oil lines to the heads. It started and ran great for a couple of days the died again. Got it back to the farm and let it sit for a day and it started again. Pulled it into the barn and it died again. Got it started again and While I was trying to figure out what was going on with it, I hit the wires that go to the oil temp sensor and it died. Had my wife turn the key while I moved those wires around and got it to start again. I did not find anything wrong with the wires that lead to that sensor. Yesterday, I pulled the chip out of thr computer and it started. I tried it several times and it started every time. Today, I started it this morning and pulled it out of the barn. I put it back in the barn, shut it off and now I get a crank no start.
I unplugged the icp and no difference. I am not sure where to look at this point

 

Is the wait to start light on, or do you have communication with the pcm?

 

Maybe it's a bad oil temperature sensor?

 

The wts light stays on all the time now. I am not getting any communication between the computer and my scanner

 

I thought about that too, so i replaced it and no difference. I have a new computer on its way. Hopefully that will solve most of the issues that I am having

 

Today, I get a no crank if the EEC relay is in the cjb. Pulled another relay out and changed it out and still no crank. pulled the eec relay out and the truck would crank. What are the chances that I have a bad cjb?

 

After tracing wires and looking at schematics, I came to the conclusion that I was missing a ground coming out of the fuse box. Pulled the fuse box out and took it apart. I found a wire in a trace that was burned. Repaired it with solder and put it back together. Put it back in the truck and now it's running.
Thanks for all the suggestions on what to check