Today while backing our 5th wheel into the driveway, the truck kept dying on me. I finally got the trailer parked and immediately changed the CPS thinking that was the culprit. But the truck continues to die when it is under a load and only seems to be doing it in reverse I can duplicate the problem by standing on the brake, putting the transmission in reverse and when I hit 15-1800 RPM, the engine just dies out. It will start right up again and run fine. There are no codes being thrown so at this point I am looking for any suggestions as to what the problem might be. This is a 2002 7.3L with Auto transmission. Thanks in advance.
Jack

 

Check the wire harness at the driver's side valve cover next to the large black connector, under the intake tube. The wiring commonly chafes on the valve cover and causes a short to ground when the engine rocks.

 

Here's a bump, to me it sounds like a tranny or t.c. issue of some sort.

 

Thanks for the inputs.....I initially was thinking transmission too. I still have a couple of months left on the extended warranty so the truck is at the dealer.

Jack

 

Don't forget to update us when you find something out Jack.

 

I will keep you posted on what they find.
Jack

 

When I dropped off the truck yesterday the problem could not be duplicated. They spent most of yesterday trying to duplicate the problem and get the computer to throw a code. I asked them to drop the transmission pan and check for debris then power flush and refill. Everything looked good from the fluid to no debris in the pan. I picked up the truck this afternoon, checked it at the dealer and it seemed fine. Got it home 45 minutes later, threw it in reverse and power braked it and at 1300 RPM it stalled out. Right back to the dealer I went where the senior diesel tech met me when I arrived. After scanning for codes (there were none) he was able to duplicate the problem several different times and he is pretty certain it is not a tranny problem. He is convinced it is a chafed wire somewhere grounding when the engine is torquing over. He did grab and wiggle a few harnesses on the driver's side in the engine compartment and the shock tower and the problem did go away. He did not go near the harness mentioned in this thread but I did talk to him about it. He will try to locate the bad wire or harness tomorrow and replace it. More to follow.
Jack

 

Welcome to FTE Jack. I'm interested to hear what they find also.

I'm not so sure it's a chaffed wire if you can duplicate the problem under certain conditions. I had a chaffed wire (the one mentioned earlier) and could not make it act the same way twice. If the tech wiggled wires on the drivers side, odds are he did try that harness also. There was a TSB mentioning that wire and the one over the shock tower, so it sounds like you've at least got a real diesel tech looking into this.

When the truck died, did it instantly cut off like someone just turned the key off, or did it cough and stumble for a second?

By the way, we have a 99 - 03 7.3 diesel section here at FTE located a little further down the main forum listing. Lot's of good info down there that is specific to your truck. Be sure to stop by and say howdy.

 

So I got the truck back today. Turns out it was a chafed wire in the main engine wiring harness in the location where FireMe described. The wire had chafed on a bolt under the air intake tube and actually polished the bolt pretty good where it had been rubbing. Once he located the bad wire he could pretty much make the truck stall at will. He explained that particular wire carries voltage to a number of relays for the entire engine so when it shorted out it just shut down. He repaired the wire, re-wrapped the harness and placed wire shielding to prevent it from occurring again. So far so good The other good news is that the repair was covered under my extended warranty. Thanks to all for your inputs, suggestions and support.

FireMe: Thanks for the point in the right direction.....it was in the harness you described. The tech said he had seen the chafing where you described before but not where he found it on my truck.

F350-6: The truck would cough once or twice and then die. If you took your foot off the accelerator when it started to cough, the truck would continue running. An interesting observation I made yesterday when the tech was duplicating the problem was that if he did not take his foot completely off the accelerator the truck would continue to run but but then pumping the accelerator after the event had no affect on the engine. I will check out the other forum you mentioned in your post.

Jack

 

Thats great news Jack, glad your up and running!

Thanks for the update.