My 2004 3500 I bought from a friend two years ago with only 77k on it is giving me grief! We use it only for hauling hay and a horse trailer periodically. Right now there's a big fire nearby and it would be ideal that it is operational to evacuate if needed, but it is not!

In January the engine started making a horrible noise at it turned out the fan clutch bracket had broken and wrapped the cable around the fan! Pricey repair and I learned that it is a flaw in this generation.

Then my husband topped off the tank at Costco in February not long after that repair. He noted a water in fuel light and so we drained the fuel canister and the light went away. Then the truck sat a good while before I needed it to get hay. When I started it, there was a CEL. My code reader pulled a p0088, high fuel rail pressure. I read up on that and saw it wouldn't be good to drive it even to a shop, prone to stalls and possible injector/engine damage. AI said FCA. I read water in fuel could corrode the FCA and cause this. I met a mechanic through work so he came out to suss things out, used his pro diagnostic scanner. The engine was really idling rough/erratic while he was running the diagnostics. When the engine was turned off, the fuel pressure remained high, indicating the FCA was toast. I ordered a new Bosch replacement. He came back and installed it and she purred like a kitten and the pressure went down when turned off like it was supposed to. We thought that was it.

A couple of weeks went by and I started the truck with no issue, backed it up to my trailer to hook up for use the next morning. The next morning it refused to start for five attempts before finally turning over. Before the last attempt, I did hear an odd noise from the engine compartment, not the fuel life pump. But then it started, and no CEL. I hauled animals to my friend's place, stopped and started a couple of times without issue, and then started again to come home. No problem.

Now it has been sitting for a few weeks and I went out today to move the truck to hook up to another trailer and low and behold the CEL is back!!! Put the reader on it and p0088, and idling roughly again! WTAF?!!!

I can't believe the BOSCH part is bad. What's the next likely culprit? I of course didn't want to drive it because I don't want to get stranded or ruin anything. I re-upped my subscription here hoping someone can give me the magic bullet.

I contacted my mechanic who is going to come back on Monday. I just don't have the time or determination anymore to do it myself, but seeking info because he's not a diesel mechanic per se or familiar with these trucks, but he's reasonable, physically capable (me, not so much anymore) and willing.

What else should we be zeroing in on with the diagnostics? Nothing else popped after re-running the scan after installing the FCA.

Last additional note of interest to me: I borrowed this truck back in 2022 before I bought it, hauled a 16 ft horse trailer to out of state to bring home a big load of livestock gates etc left behind when we moved. It got 16 mpg hauling. After I bought it, it would only get 13 mpg hauling lighter loads. I thought after replacing the FCA that it might improve but hauling that load of animals I was back down to 12-13.

Edited Saturday at 10:14 PM2 days by DIYGirl

I am just following down your post in order of events. Thanks for providing good detail, but I still have a couple of questions.

On 7/18/2026 at 3:10 PM, DIYGirl said:

Then my husband topped off the tank at Costco in February not long after that repair. He noted a water in fuel light and so we drained the fuel canister and the light went away. Then the truck sat a good while before I needed it to get hay. When I started it, there was a CEL. My code reader pulled a p0088, high fuel rail pressure.

Did you replace the fuel filter. Have you replaced the fuel filter since this event?

On 7/18/2026 at 3:10 PM, DIYGirl said:

A couple of weeks went by and I started the truck with no issue, backed it up to my trailer to hook up for use the next morning. The next morning it refused to start for five attempts before finally turning over.

Just for clarification - "turning over" means the starter is cranking the engine, but the engine is not running. Can you give more detail to your particular "no start" situation?

On 7/18/2026 at 3:10 PM, DIYGirl said:

Now it has been sitting for a few weeks and I went out today to move the truck to hook up to another trailer and low and behold the CEL is back!!! Put the reader on it and p0088, and idling roughly again! WTAF?!!!

Has the fuel filter been replaced after the "water-in-fuel" incident?

On 7/18/2026 at 3:10 PM, DIYGirl said:

I borrowed this truck back in 2022 before I bought it, hauled a 16 ft horse trailer to out of state to bring home a big load of livestock gates etc left behind when we moved. It got 16 mpg hauling. After I bought it, it would only get 13 mpg hauling lighter loads.

I think that the 16 mpg hauling a heavy load is unrealistic. The 12-13 mpg sounds more reasonable - even with the lighter loads. Unless loads are weighed and fuel tank fill-ups and driving conditions are documented over a long period of time and trips, the reported fuel economy is very subjective and usually inaccurate.

The common rail fuel system (beginning in 2003 for Dodge Cummins engines) runs at much higher fuel pressures than the '99 VP44 engine that you have become familiar with. Consequently, the common rail engine fuel system (including the high pressure pump, FCA, and injectors) cannot tolerate any foreign material in the fuel system. Introducing water means that other foreign matter (dirt) is being introduced as well. More than likely there is much more foreign matter remaining in the fuel tank from the original source of contamination.

Also, since the common rail fuel systems is completely computer controlled, good electrical continuity is extremely important. Batteries in poor condition can intermittently set diagnostic trouble codes. For example, the FCA operation is controlled by the ECM and related wiring and wiring connections. Improper voltage in any part of this circuit could lead to a performance issue with the FCA. The FCA mechanical valve portion could have foreign matter lodged in it, which could result in the valve sticking. This could happened even with a new Bosch FCA if contamination is still present.

In almost all diesel engine applications (even before the common rail fuel system), any time water was introduced into the fuel system, the fuel filter needed to replaced multiple times until the contamination was cleared. Sometimes the fuel tank needed to be removed and cleaned.

You do need a mechanic with good diagnostic skills and knowledge of the Cummins common rail fuel system. I have been turning wrenches professionally over half of my life and am skilled in many areas, but I cannot skillfully diagnose a common rail fuel system symptom.

• John

Edited 15 hours ago15 hr by Tractorman

On 7/18/2026 at 3:10 PM, DIYGirl said:

In January the engine started making a horrible noise at it turned out the fan clutch bracket had broken and wrapped the cable around the fan! Pricey repair and I learned that it is a flaw in this generation.

Also, I forgot to respond to the above. The bearing likely seized and resulted in a broken bracket. My brother-in-law's 2003 truck had a loose / noisy fan hub bearing, which was caught on an inspection. If gone unnoticed, the same result could have occurred.

I periodically remove the serpentine belt and inspect all pulley bearings. They will fail - the inspection just stops it from being a catastrophic failure.

• John

Edited 15 hours ago15 hr by Tractorman