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rag_ftw · 11-19-2021, 07:13 AM

2003 ISC 350 with CAPS. Getting intermittent ENG PID 94 10, Fuel Delivery Pressure, abnormal change with approx 20% eng derate when light is on.
Changed fuel filter, no help.
No visible fuel leaks on prestart or after engine is running.
What say ye Cummins experts?

wolfe10 · 11-19-2021, 07:23 AM

Other than a restriction due to fuel filter restriction plus long run from tank, AIR getting into the fuel system can cause that. Leak could be at the filter, at the lift pump (a prime candidate) or in the fuel line itself.

Make sure the lift pump is tight and not leaking fuel (which would suck air in when under the vacuum of engine running.

rag_ftw · 11-19-2021, 07:40 AM

Quote:

Originally Posted by wolfe10

Other than a restriction due to fuel filter restriction plus long run from tank, AIR getting into the fuel system can cause that. Leak could be at the filter, at the lift pump (a prime candidate) or in the fuel line itself.

Make sure the lift pump is tight and not leaking fuel (which would suck air in when under the vacuum of engine running.

Changed fuel filter - no change in symptoms
No visible fuel leaks before or after engine start.

If it was an air leak I would think it would be constant and not intermittent. Is this not good thinking?

wolfe10 · 11-19-2021, 07:45 AM

Quote:

Originally Posted by rag_ftw

If it was an air leak I would think it would be constant and not intermittent. Is this not good thinking?

Not necessarily. Higher engine load= more suction on fuel line. If air leak, it could be load dependent.

Cold vs warm engine could also be a factor-- parts expand with temperature and contract with cold.

Agree, if massive leak, symptoms should be more constant.

With the high incident of failure of the lift pump/leak at the lift pump, were it my engine, I would sure check it out. Only takes a few minutes.

Could it be something else-- sure. But start with the low cost/high failure rate stuff before considering "worse case" items.

TR4 · 11-19-2021, 08:11 AM

I agree with wolfe10, check the lift pump and fuel lines. Diesel fuel is nearly an incompressible fluid, so ANY air in the lines going to the CAPS pump reduces fuel pressure to the injectors.

Bill

Caliber · 11-19-2021, 11:47 AM

Quote:

Originally Posted by rag_ftw

2003 ISC 350 with CAPS. Getting intermittent ENG PID 94 10, Fuel Delivery Pressure, abnormal change with approx 20% eng derate when light is on.
Changed fuel filter, no help.
No visible fuel leaks on prestart or after engine is running.
What say ye Cummins experts?

Use the trouble shooting guide, when it's acting up start at step 4b.

jacwjames · 11-23-2021, 04:33 PM

If you are not a member of the Cummins Quickserve site I'd suggest you join.

I had the same code come back in July/Aug. I was letting the engine run while fueling and it started to stumble and puffs of black smoke came out. Checked my Silverleaf diagnostic and it showed me the code but it was inactive. It has not happened again.

This is what I got off the Quickserve site, you can actually search for the fault code and it will supply documentation as how to troubleshoot.

Based on what I found it could be your fuel pressure sensor and or problem with the wiring harness.

rag_ftw · 11-23-2021, 06:53 PM

Thanks, Jim. I won't be able to work on it again until after Thanksgiving.

Additional info: Started when we left Salt Lake and initially it was just 3 or 4 times when we first started rolling. Once everything heated up it didn't repeat. As the trip to FTW continued it happened more frequently and by the time we got to FTW it was happening every few minutes and didn't stop when everything warmed up. Doesn't seem to be throttle related. It will happen from 1/2 to full throttle. Check engine and derate will last from a couple to 30 seconds.

rag_ftw · 11-29-2021, 06:02 PM

Once again you guys led me to the problem. Looking at the pressure sensor I noticed one of the three wires had come out of the connector. Stripped off some additional insulation, stuck the wire back in the connector, added another piece of wire to tighten everything up and covered the top of the connector with potting compound. No 94-10 (456) fault code and check engine light is out. That was a $320.00 savings!

Thanks gents!