ODB II Code P0251

[duallypilot]

My 97 stalled tonight waiting at a stop sign and the SES light came on and stayed on. Got it started and drove it Autozone so they could put scanner on it for me. It came up as code P0251 which is "Injection Pump Cam System".
Can anyone explain in a little more detail what I'm looking at here?
The scan did clear the SES light, and the truck ran fine for the rest of my errands, but has me intrigued.
Jerrald

 

[ak diesel driver]

are you using any additives in your fuel?

 

[duallypilot]

I did on the first fill up ( only have had to fill it up twice since we got it last month). I put some Diesel 911 in the first tank just incase the dealer we got it from put junk or contaminated fuel in it. The second tank was straight BP fuel from a reputable station near the house.

 

[NVW]

I've heard air in the lines can cause codes, put a clear line on the return fitting on the IP and look for bubbles.

 

[ak diesel driver]

ulsd is very dry and can shorten IP life without a lubricant added to the fuel either 2 stroke or ND30wt. x2 on what Leo said

 

[great white]

I dropped both the 2 stroke oil and the ND30W in mine.

I use an additive in every fill though.

P0251 is usually related to the Optical sensor. As already mentioned, air in the fuel is a likely culprit.

Follow the gents advice above and see what you get.

You haven't run the truck very low on fuel lately have you?

 

[great white]

(expansion on my post above, mods please correct)

I dropped both the 2 stroke oil and the ND30W in mine.

I use an additive in every fill though.

P0251 is usually related to the Optical sensor. As already mentioned, air in the fuel is a likely culprit.

The sensor has an optical "eye" that is looking for a pulse signal from a wheel with "windows" that it "looks" though inside the IP. This gives a hi and low resolution cam position signal to the PCM. The sensor is calibrated to look through fuel, not air. When a bit of air gets in the way of the sensor (doesn't take much), it gets a bit "discombobulated" and the PCM may set a trouble code thinking the sensor has a problem.

Follow the gents advice above and see what you get.

You haven't run the truck very low on fuel lately have you?

That can introduce air into the system with a low level and a sloshing tank.

Albiet a temporary condition rectified by simply refilling the tank.

Personally, my fill point is whenever I get below 1/4 tank on the "wildly inaccurate" stock dash gauge....

 

[duallypilot]

Truck seems to be running fine this morning. Went to the parts store and got some Lucas Upper Cylinder Lubricant and added the suggested dosage to the tank. I'm a big user of Lucas products, so we'll see if the code comes back.
Thanks again for all the replies, I know I can count on a sensible response when I ask a question on here.
Jerrald

 

[guybb3]

Sometimes that code is related to fuel supply as well as quality of fuel.

 

[JMJNet]

Diesel 911 is actually pure alcohol and should not be used as a diesel additive unless the fuel is frozen/gelling.
It is not designed to be used continously in every tank.

Alcohol will dry up diesel fuel to the point where the lubricity is probably close to 0.

Just a warning.

My suggestion is to read the MSDS next time before using an additive.

The solution is probably just to put good diesel with good/proper diesel additive.
2 cycle oil (TCWx) have been known to increase diesel fuel lubricity.
Some have even put Non-Detergent motor oil, not too much though.

 

[btfarm]

The fuel suppliers are required to blend in a lubricity additive before they go to the retail stores. You can check that out with Greg (Crankme69-our refinery guru ). It may not give us critical folks a secure feeling so a good quality diesel fuel additive is always a good choice and IMO not a waste of money (I'd say it's cheap insurance). Personally I use Power Service Silver bottle Spring through Fall and White bottle Winter. PS 911 is ONLY for frozen/gelled emergencies because it's an emulsifier and will send water through the system. You don't really want that if you can avoid it.
An occasional dose of 2 cy, trans fluid or ND motor oil probably won't hurt if it makes you feel good but I question whether it's a better additive than those formulated for the job.

 

[JMJNet]

NO TRANS FLUID, either!!!

The modern trans fluid has too much additive (friction modifier) which is good for its purpose as trans fluid but not as fuel.

If you can get a new trans fluid that at least 30 years old, then you can put it in there since it may not have all those additive.
This is something that people in the early diesel likes to do but it is also detrimental to the IP.