I wrote in about this before and there were some good suggestions for what to look for. But I still have the problem and can't figure it out. This has been going on for a few years now. I've tried some of the suggestions which was checking all the connections under the hood, cleaning them, dielectric grease etc.

I have a late '99-350 that will quit while driving down the road, like you shut the key off. This usually happens going over RR tracks or hitting a nickel [very small bump] in the road. This happens at least once a day or five times a day, depending how much loose change has been tossed onto the road that day! Also shuts off alot when shutting the pass. door and sometimes the driver door.
I'm on my third CPS so thats not the problem, I changed them in desperation hoping I might have bought "some" bad ones. I've got two spares now.
It gets scary trying to get the truck into neutral,turn key off and restart, while driving in traffic or in the middle of a turn, you get the idea.

Awhile back there was a guy that broke down on the road and you guys were helping him figure out what the problem was. He eventually took it to the dealer and I believe he said there were some shorted wires on the valve cover [drivers side] which I checked, OK. I think the dealer told him there were other known places that the wires will chafe on psd's, the steering column and another place, I'm not sure.

How do these trucks shut off? is there a fuel shut off? do all the injectors shut off at the same time? The steering column with ignition wires running in there seems to be my next place to look.

My wife wants me to get rid of it but I don't. I'm sure it's a small problem causing big problems. What do you guys think?
Sorry for the long post. Dave

 

You say you posted these problems before, I can't find any posts.. But, anyway have you had your fault codes read by a compatible scanner for a powerstroke? If not, it is a good place to start.. Have you had the truck since new? Have you ever had the valve covers off? The reason is there is a 9 pin plastic connector under each cover that sometimes come loose.. Mine did at 70K. You loose your injectors and or your glow plugs. But usually it will just run rough and does not shut your engine off.... Do you loose all electrical power when it happens.?

 

I am still a novice on diesels, however I suspect that there is a broken or fraid wire coming from the CPS. The sensor is probably good but it sounds like maybe the connector is bad. Try hooking up a meter and see if you can ohm the wires out. If you can then wiggle the wire a little and see if there is a change. Make sure the power to the truck is off. Good luck.

 

Any codes? SES comes on? Anyone you know have AE that can connect and save data while driving over one of these bumps. Otherwise it sounds like you have checked almost everything else. It sounds like a loose connection since it only happens on bumps. I would say possible short in wiring, sad part is it could be anywhere. When did this 1st happen? If it started soon after replacing a part that is where I would start. I hope you find it!!!!!!

 

Only a few things will shut one off cold. Fuel is not one of them. If fuel stops it will stumble and not start very easy. Your problem is going to be electical. The CPS or CPS wiring would be most likely place to start. Other places to check would be some of the main wiring harnesses and plugs. Most of these will be on the drives side near the firewall and master cyl. There are some wires on the steering column that can short and do the same thing but usually blows a fuse. Only other places I can think of it the PCM itself or a loose fuse or fuse holder that powers on of the major circuits. A bad connection at any of these places will shut it down cold.

 

Oh yeah, meant to ask, does it always start back with no problems?

 

I was that guy that broke down on the side of the road (thanks for remembering me)
The 3 places the mechanic said to check were the main engine wiring harness (at valve cover and above cover at metal bracket), steering column wiring harness, and a wiring harness that goes over the drivers side front shock.

The electrical issues usually result in a short to ground which causes the PCM to reset. If it throws a code it will either be a KAM code or something that will make them want to clean your battery terminals.

Do you get any dash lights that come on, flash, etc. that are associated with your problem? Do you have a chip in your truck? A loose chip can cause the same problem.
There was also a problem with some of the 99's where the windshield would leak and cause problems with the PCM. You might check for any signs of moisture next time it rains.

I've still got photos of where to look for the main engine wiring harness if you need them.

Good luck. I know how these electrical gremlins can be.

 

Had a 7.3 owner tell me after I got my 7.3 that if you have too many keys hanging on the ignition switch that it can cause problems like that after a while. I guess that the tumbler can't take much weight on it. HTH

 

If you've ever taken the ignition switch out I don't think you'd be concerned about this. The size of the off/run/start switch is fairly robust, but there have been problems with the wiring running to the switch.

Because I'm too old to know, what does HTH mean?

 

Well I sure appreciate the responces, alot of questions to answer.
The truck will start right back up if I turn the key off first, If you just try to start it, it won't fire. So by turning the key off it must reset something.
I had a friend hook up a computer thingy that records just about everthing on the truck for about a week and it did quit several times during that period. Did not record any codes.
I am thinking that the problem is not on the motor because the shaking and vibrations of the motor would make it quit without hitting bumps. The motor is on rubber mounts and is isolated from the frame, I don't think shutting the pass door would transmit through to the motor.
I have disconected the chip and trans comand andd it still quits with these off, so thats not the problem.
The CPS wires and or conection could be a problem but again, thats on the motor and I don't think that could be it but I'm gonna check it.

All the dash lights come on when it quits, no flashing though and as soon as it starts they go out.
I like to fix things myself [or at least help my machanic friend fix stuff] saves $$. But maybe I am getting to the point that I should take it to the dealer and let them drive it around with their computer thingy hooked up to it. It's gotten to the point that they won't have to drive it far before it quits again.
I'm going to look into some of the suggestions above, Please keep the ideas coming and thanks again for the help.

Dave

Oh yea I did try knocking on the PCM to see if it was loose or if that was the prob but it kept running.

 

I missed the part about closing the doors, That sounds to me like it has to be in the cab. Under the dash is where the PCM is located and all the wires connected to it. I would start the truck and lay on the floor and put my hand on every wire I could possibly reach and wiggle things around some. I got a feeling when you hit the right place you will kill the engine. Also move the tilt steering up and down. Might even do some bumping the column with hand. If that fails to show anything, open the hood and do the same thing. Bump the Power Dist. Box, wiggle wiring harnesses around, if something under there does kill the engine, start with looking at the relays in the PDB and see if one is loose.

 

HTH = Hope this helps

 

My computer is at my business and we're off work, but I come in to check tthis thread. I did poke around under the dash over the week end, moved some wires around. It quit on me yesterday. I'm thinking that it's under the dash as well or on the fire wall, somewhere on the body or frame of the truck. I'm gonna keep looking, thanks for the input. Dave

 

Did you make it quit while moving wires around?

 

Just a thought, but maybe if you know where your ground straps are for the cab, could be that they are loose. I had a truck once that the ground jumper broke off and the only thing to ground everything in the cab back to the battery was the gas pedal. With sensors running everything now, no longer have a pedal for ground path. HTH Lee