Sometimes it will run perfect. Then start running really rough. I watched my rail fuel pressure. About 6700-6900 at idle. About 17000 at 40 mph. It doesn't matter if the engine is cold or hot. This is a 20006 5.9

 

The Fuel Control Actuator (FCA) is an electronically controlled solenoid valve. The ECM controls the amount of fuel
that enters the high-pressure pumping chambers by opening and closing the FCA based on a demanded fuel pressure.
When the FCA is opened, the maximum amount of fuel is being supplied to the fuel injection pump. Any fuel
that does not enter the injection pump is directed to the cascade overflow valve. The cascade overflow valve regulates
how much excess fuel is used for lubrication of the pump and how much is returned to the fuel tank through
the drain manifold.
An audible click from the FCA is normal when operating the key from the ON to the OFF position.If the Cummins 4932457 FCA / Fuel Control Actuator is not correctly functioning; this results in the Engine Control Module / ECM cannot determine the fuel flow rate supplied to the CP3 Fuel injection Pump. In most cases, people first know there is an issue when they have a hard start or no start issue because the FCA will not allow the pump to build pressure to start correctly. However, by the time this symptom occurs, the truck has probably been delivering less than they genuinely desired amount of fueling for a while already as the FCA is a simple spring design that many times takes a rather slow death and not an immediate failure. The Engine Control Module / ECM uses the fuel control actuator to control the fuel pressure in the common rail Dodge Ram diesel. The Fuel Control Actuator is an electronically controlled solenoid valve. The ECM controls the amount of fuel that enters the high-pressure pumping chambers by opening and closing the FCA based on demand. The FCA is the device that controls the fuel pressure delivered to the common rail to provide fuel delivery rates.

What are the symptoms of a failing 5.9L Cummins Fuel Control Actuator - FCA?

• Hard Starts
• No Start Condition
• Rough Idle
• A Rattling Noise from the engine, which sounds like Fuel Knock.
• You have decreased the engine power output level.
• Engine operation is rough.
• Engine RPM surging

A faulty fuel pressure regulator causes these symptoms. Replacing your 5.9L Cummins regulator can resolve your problem.

Hope this helps
FF_2111

 

When I bought my 2005 at 22K on the odometer it would sometimes run really rough when started. It acted like one cylinder was not functioning, maybe two cylinders. After I let it idle for about a minute or less it would smooth out and be fine. It would then run fine until I shut the engine off. Not always but sometimes when recranking the engine after it had been off for several minutes it would do it again. Very intermittent problem. The dealership replaced two injectors as his diagnosis revealed two cylinders not producing as much power as the others. I don't know if this was a code in the engine computer or just his diagnostic device. He replaced two injectors. When he finished and re fired the engine it did it again setting right there in the garage!!! It was quit time and the mechanic said to bring it back.

Well I was cruising through Wal Mart that evening and saw they had a good selection of Power Service Diesel Kleen in the grey bottle. I had read on some of the forums about this product and decided to just try a dose or two. I'm not a believer in easy fixes like this. But Wal Mart does not stock merchandise that does not sell good so there must be a good demand for this product. However to my surprise it totally corrected my rough idle!!!!!! Never did it happen again!!!! Not once!! I continue to use the recommended dose now at each fill up and have put almost 100K miles on my 05 in the past 12 years. It's supposed to clean the injectiors and raise the cetane level or something. I'm a firm believer in using Power Service Diesel Kleen.