I have a 2000 F-550 7.3L auto, 4WD bone stock - 143K mi. Early this summer I noticed an occasional and very intermittant change in the sound of the engine, accompanied by a very slight surge or jerk. The problem became progressively more frequent and noticeable over a month or two, but presented little problem to driving. Leaving work one evening, I drove about three miles and the engine started making the sound changes and slight surges, then suddenly just shut down 100%.

I was working out-of-town so the truck went to a Ford dealership. After a call to the Ford Dealer Tech Support Center, they diagnosed the problem as a shorted wiring harness to the injectors under the left valve cover. They gave the truck back to me, but it was obviously running on only 6 or 7 cylinders (it had always been smooth as silk). More diagnostics and they said the shorted harness must have blown the computer. A new computer and $1400 later I was back to normal - for awhile.

The exact same symptoms started again about three weeks ago and are getting progressively worse as usual. I wonder about the other harness under the right valve cover, or if I'm even on the right track. The only symptoms are the change in the sound of the diesel knock and the slight surge/jerk. My mechanic has an $8k analyzer, but it seems stumped and throws out bogus codes. It's most noticeable under easy to moderate driving and occurs under both hot and cold engine temp. Injectors check OK on the analyzer. Any thoughts would be much appreciated on this head-scratcher. Thanks.

Towerjack

 

Wow.. First thing i would change is the CPS sensor, less than $25. If that does not fix the prolem i would pull both valve covers and check the plastic 9 pin connector for looseness and inspect the wiring harness to your glow plugs and injectors..(a common problem). I doubt very much you needed a new computer.. You need a scanner capable of reading 7.3 diesel fault codes.. They are a lot of good people here on the forum that will help you fix your truck.. Welcome to the Forum !

 

first off, look on your driver side plug that goes over the Valve Cover. lots of people had the harness rubbing on the VC and shorting the wires. that would be your starting point. its the one that goes through the metal bracket , its touching VC , and its easy to disconnect it and inspect it.
second, your Under VC harness might be loose, on the other side and causing stupid symptoms, and codes to be thrown, but you have to take the VC off to verifie and phisically inspect it.
if you going to need UVC harness let me know i have good spare ones i can ship it to you ,

 

ohhhhhhhhhh and Welcome to FTE......................

 

Also here is a link to help you with the fault codes
http://www.clubfte.com/users/screwy/73d.html

Here is a link to show you how to change a CPS snesor..
http://www.7point3.com/mods.aspx

 

if you going to need UVC harness let me know i have good spare ones i can ship it to you ,

Still cant find any takers for that harness ay.Keep trying you'll get a fish someday.

 

LOL thats what i said 2 posts above LOL


i guess noone wants them.