7.3 won't start (sometimes)

[NewX]

This has me baffled. I have an 02 X 7.3 and sometimes it will turn over and run fine, other times it won't. I've installed two new batteries and a new starter. When I turn on the ignition switch, I can hear everything cycle like normal, but when I turn the key to crank the engine, nothing. Occasionally, after many attempts to start a black box on the passenger side over the wheel well will turn on. It looks, sounds like a vaccum pump. I checked the batteries, and one is 12.45 volts and the other is 12.47 volts.
Update. Now it won't start at all. I plugged it in all night thinking it might be affected by the cold. Still no go. I did disconnect both batteries and checked them individually, one at 12.75 the other at 12.35. I going to pull the new starter and have it tested. Any other suggestions?

[kc8yhk]

tried changing the cps? when you crank the engine does the tach move at all?

[HighwayPrisoner]

Questions, Is the shifter sloopy? Try moving the shifter, while holding the key in the start position, or move the shifter to neutral, and wiggle. Do you have brake lights, should start in neutral even if the brake light switch is bad. The tach on an 02 will not move like the earlier trucks with a good or bad CPS. Try removing the chip, they usually will let the engine crank, but not start, but it is worth a try. The starter could be defective, but try these other things first. One more thing, there is relay in the main fuse panel next to the rear window defogger, which you don't have, take this relay, and use it for the starter relay, they are the same. Hope this helps.

[NewX]

I was wondering about the CPS. Would the truck still crank with a bad CPS. Right now, I can hear the fuel pump and the GPR, wait until the lights go out and then turn the ignition, nothing happens. There isn't even clicking from the starter. I've even tried starting it in nuetral to rule out the nuetral safety switch. I do have another CPS so I could give it a try.

[HighwayPrisoner]

Yes it will still crank with a bad CPS, but won't start. Definately check the starter relay in the fuse panel. A friends 02 did this recently, same symtoms as yours. This is easy, and the relays are the same, Ford gave us a free relay.

[NewX]

Which fuse? I assume you mean the fuses inside the vehicle. I did get it to turn over once this morning. Would a fuse allow this to be spordic starting. I thought if a fuse was bad, it either is or it isn't.

[HighwayPrisoner]

It is not a fuse, it is a relay in the fuse panel left side of dash. Check the owners manual for the diagram. I would go out, and check my truck, but it is in the body shop. Your truck definately has the starter relay symptoms. If this is the fix, it will save you more trouble, and is an easy fix.

[NewX]

Thanks. I check it out and report back on the outcome.

[HighwayPrisoner]

Hope that is the fix.

[NewX]

Gentlemen I appreciate the responses. The relay was the problem. Starts and runs great. I just donated to the site to help keep the information flowing to other people in need. Thanks again.

[HighwayPrisoner]

NEWX, hold up a minute, donate to the Highway Prisoner Relief Fund!