Truck: 1999 2500 Quadcab NV 4500 300,000 miles.

 

What happened:  I was driving to work and everything was fine until I pulled up to a red light then my truck could barely hold a very unsteady idle.  CEL came on.  Pulled off road and had it towed to my work.  Pulled following codes:

 

P0251 Injection pump fuel valve feedback

P0252 Injection pump fuel valve stuck

P1688 VP44 Fuel Injection Pump Module Internmal membory or A/D error

P1693 Fault in companion module

P0122 TPS sensor 1 circuit low

P1682 charge system output low

 

Some of these were probably very old, I can't remember the last time I did a scan.    I should also mention I have a BD FlowMax lift pump with primary and secondary filter and two pressure gauges and it runs around 15-17 psi.  Cleared and rescanned and the injection pump codes and companion module came back.  The VP44 had been on my mind for a while.  It was at the very least 150-200K miles old, probably older.  Bought a new VP44 and installed it.  Truck fired up and ran fine with the following exceptions:

 

1. Idled at 864 RPM and it used to idle at 800RPM without fail.
2. When I turned on the A/C my Edge Insight used to register a small engine load but after new I.P. install showed 0% load with A/C on.
3. EGT was a little higher which I attributed to a possibly higher fueling rate with a nice new pump.
4. After the engine was hot, it would have a slightly unsteady idle with a seemingly random miss every 1-3 seconds

 

I talked to the diesel shop and he put a note on my file with the condition and we discussed that it could be a connector tube was unhappy have being disturbed from a long sleep where it was or possibly an injector.  Injectors also had at the very least 150-200K miles, probably much more.  Could be original for all I know.  I decided to install new injectors and new connecting tubes.  Before they came in, I didn't drive my truck for 7 or 8 days and when I started it up to go to work it was smoking and idling a little funny.  I figured maybe a dribbling injector let some fuel down and figured it would clean up.  Got a few hundred meters [yards] down the road and it seemed to lose about 75% of its power so I turned around and parked it.  Seemed to go back to normal power once or twice.  Since then the injectors came in and I installed them and its still got the same problem.

 

Right now my thoughts are the following:

1. Probably the injection pump.  I'm thinking probably bad pump but there is a small chance that the woodruff key could have marred a bit on install but I was very careful when lining up the shaft to the injection timing gear. Note: I was INCREDIBLY careful to keep everything clean.  Thoroughly cleaned the engine before working on it.  Changed the fuel filters and flushed the whole system up to the VP44 before connecting the fuel line to the VP44.  Flushed about half a gallon or more of fuel.
2. Possibly a crankshaft or camshaft sensor
3. Possibly (but hopefully not) ECM or maybe even PCM
4. Maybe APPS making it do weird stuff?
5. Head gasket?  Hopefully not.  Cooling system not bubbling, no coolant in oil or oil visible in coolant.

 

My plan of attack is:

1. Scan the truck with my boss's good scanner.  If there's codes then see where that leads.
2. If no codes MAYBE change the crankshaft and camshaft sensors.  They are a real bugger to get to and I don't like changing things for fun, but maybe?  What are the odds they are giving bad data and not throwing codes?  My understanding is if the VP44 and and the camshaft position sensor disagree you get a code.
3. Pull injection pump.  Assess woodruff key.  Maybe send it back.  Injection shop is going to contact the rebuilder.
4. Not sure how to diagnose ECM or PCM other than by process of elimination....

 

Any thoughts, as always, are very appreciated!

 

There are some of us that let there Cummins sweat horsepower.  After 458k miles they tend to get well rather greasy grimey and dirty from being driven to numerous other states. 476k miles I will be to the moon and back. 

Edited January 9, 20232 yr by Mopar1973Man

1 hour ago, Mopar1973Man said:

 476k miles I will be to the moon and back. 

Then your nickname will be Alice....

 

BANG, ZOOM

🤣🤣🤣

No. I'm going to pack up again and make my second trip to the moon again.