Hey All,

I hate to post this because I wouldn't want to duplicate posts. I've searched but found no satisfaction! I purchased my first 7.3 diesel last summer and it ran perfectly well until about a month ago. I was driving down the road and it lost all power. Pulled it over and shut it down and then it wouldn't crank. Replaced the CPS with a grey CPS and it still wouldn't crank. Disconnected and reconnected the batteries and it finally cranked. I got it home but it's been unreliable since. Even if plugged in it'll take half a dozen cranks to get started and when it starts it's really rough. If I give it some fuel it will smooth out but will at random get rough again and sound like it's on the edge of dying. While driving it will be driving perfectly fine and then lose all power at random. Sometimes it comes back to normal and sometimes I have to pull over and shutdown and restart. I replaced the CPS again (another grey one) and there's no change. I've also replaced the fuel filter last week which I had done last summer when I first bought it as well. It was pretty dirty but too bad. I only drive it every other week or so. I was a quart low on oil so I put Lucas in it to see if it would help anything. In other words, I'm lost. Can multiple CPS's be bad? My truck stats are below:


1997 Ford F350 7.3 with 195k miles. No mods other than a break assist system. I really appreciate your help in this!

 

If you purchased the CPS's from a parts store then yes, most of them won't work reliably. If that is the case purchase another one from Ford or International only. They are dark gray (almost looks black in dim light) with a purple o-ring.

Don't apologize for posting and welcome to FTE.

 

If the CPS is a good one then I would check the valve cover harnesses. Pull the connectors and check the pins you may have one burnt

 

I would check all the battery/ground connections to the relays and ground contacts to the frame, motor, and engine block. Make sure all the lights are working. If you've installed any kind of LED or HID lighting, those have been known to cause some issues. What kind of oil are you using. Lucas oil additive is not recommended in these trucks.

 

X2!
Was the fuel filter black when you changed it? A black fuel filter indicates leaking injector o-rings.

 

If you know anyone with an obs in your area ask to borrow their injector driver module (idm) gray box on drivers side fender with a massive plug. If they start to go bad they can act just like this. Mine did... also you can see if the roughness is caused by a certain side or certain injectors. While running rough unplug one valve cover gasket plug at a time and if the roughness doesn't change when a certain one is unplugged those cylinders are the source.

 

Maybe a sticky IPR?

 

Hey rlandson, where are you located?

 

I would drain the oil and get the Lucas out of there. These engines do not like oil additives. This is because of the high pressure oil system. It can pressures of up to 3000 psi, and under those high pressures, additives will foam aerate the oil, making the fuel injection system not work properly. The injectors run off this high pressure oil. You may have made your issue worse, or even created another one.

 

he is in Tennessee

 

Do you know what part?

 

no, just looked at his user profile

 

Hmm. Where in the Volunteer state do you live?

 

Bird


That was what was bad on my old truck....I ran just like Lansdon described.


Bought one from Raff............Dang $ 135.00 for something that looks like a oil sending unit


Many Thanks to my friend Mr. Rebill for finding my problem

 

Glad I could help buddy!