Home How-to Articles 5.9L Cummins CRD Injection System Cleaning

5.9L Cummins CRD Injection System Cleaning

by Moses Ludel
S.U.R.&R. makes fuel injector cleaning on the engine possible. The FIC203 kit can simulate fuel pump pressure and isolate the fuel filter and injectors from the tank pump. Pressure is adjustable to actual fuel pump pressure to run the engine from the fuel/cleaner cannister. We use this system for both our Cummins CRD and the Jeep 4.0L EFI/MPI gasoline engine. Our shop also has an Autool CT200 for off-the-engine bench cleaning and flow testing of Bosch-style gasoline EFI injectors.

Maintaining Expensive Injection Components…

Routine Cummins CRD injection system cleaning can help protect the expensive CP3 pump and Bosch injectors. Our regular service includes two effective methods for restoring fuel injector spray patterns, maximizing performance and improving fuel efficiency.

For purging contaminant debris and flushing the injection system, we use Sea Foam Motor Treatment. One delivery method dovetails with a simple OEM fuel filter change. The other method involves our proven use of the S.U.R.&R. FIC203 Injection Cleaner Kit.

Caution: Review the how-to video and details on our methods for using Sea Foam Motor Treatment. There are also details on our 2005 Ram’s 5.9L Cummins diesel fuel system and its features. (Depending on year, make and model, your truck’s diesel fuel system may be entirely different.) Compare fuel system features and determine which Sea Foam delivery method will work best for your truck and diesel engine application.

The fuel filter gets replaced routinely. We pour Sea Foam into the fuel filter canister, install a new fuel filter and run the engine for 60-90 seconds. Shut the engine down and allow Sea Foam Motor Treatment to heat soak the injection system, combustion areas and upper cylinders. After a 20-minute heat soak, a run under heavier throttle got results: smoother, stronger throttle response plus a gain in fuel mileage!

We pour Sea Foam Motor Treatment into the OEM fuel filter canister during this routine service. Sea Foam will also be added to the fuel tanks at diesel fuel fill-ups. Although no cleaning or maintenance will prevent normal wear, preventive care can extend parts life and improve performance and fuel efficiency!

SUR&R makes a variety of automotive service tools for shops and serious DIY
enthusiasts. Among its many useful tools are the SUR&R fuel injection testing and
cleaning kits for gasoline and diesel engines.

In this service procedure, we use the SUR&R ‘FIC203’ Injection Cleaner Kit to
clean this 24-valve 5.9L Cummins ISB engine’s CP3 high pressure fuel pump, fuel
injectors and combustion areas. The SUR&R FIC203 kit will supply pure Sea Foam to the OEM fuel canister—the engine will idle unloaded on pure Sea Foam Motor Treatment. SUR&R’s air pressurized fuel canister can be adjusted to deliver Sea Foam at the same pressure as an OEM “lift” pump or fuel tank electric pump module.

Understand the design and function of your truck’s fuel system when considering the FIC203 method. If in doubt, use the simpler OEM fuel filter canister delivery method during routine fuel filter changes. On our Cummins 5.9L CRD system with electronically controlled fuel injectors, we use both delivery methods when servicing the engine with Sea Foam Motor Treatment.

The factory in-tank electric fuel pump gets disabled temporarily during the SUR&R FIC203 cleaning procedure. The air pressurized fuel canister is set to a steady 11 PSI, simulating the OEM fuel supply line pressure for this engine at an idle with no load. Bring the engine to operating temperature before beginning this cleaning process. The engine should be warm when injecting Sea Foam Motor Treatment.

When fueled by the FIC203 kit and started, the warm engine ran at an idle for over a
minute on pure Sea Foam before the canister ran out of fuel. While the engine idled on Sea Foam Motor Treatment, excess Sea Foam returned to the fuel tank. After stalling, the fuel system was primed before attempting a restart. Priming the fuel supply system is not difficult on the 2005 Ram model with an in-tank OEM electric fuel pump…Take time to watch the how-to video for in-depth details on the Sea Foam cleaning procedures.

We heat soaked the combustion areas and injectors while refilling the FIC203 canister
with a second can of Sea Foam Motor Treatment. After a 20 minute heat soak, we restarted the engine with the FIC203 set to 11 PSI, idling the engine until the second canister was empty. The engine then heat soaked for another 20 minutes.

This fuel supply system has a return line to the tank (line with the white retainer clip). Some Sea Foam returned to the fuel tank during the FIC203 cleaning process. On this EFI system, the excess volume of fuel from the fuel supply line’s lower pressure/lift pump returns to the fuel tank. Sea Foam Motor Treatment in the fuel tank will help keep the fuel injection system and combustion areas clean.

For some fuel systems, SUR&R suggests blocking the fuel return to deliver all FIC203 canister fuel to the engine. We did not block the return flow and allowed the system to return excess fuel to the fuel tank. Excess Sea Foam returned to the fuel tank through the fuel return line (white retainer clip). We periodically add Sea Foam Motor Treatment directly to the diesel fuel tanks at the ratio recommended by Sea Foam®.

The fuel supply line from the OEM fuel tank attaches to a pipe at the fuel filter canister. The 3/8-inch hose fitting uses a retainer clip in the hose end. These clips are readily available. (The Dorman 800-498 5-piece package was found online at Amazon.com.) As a precaution, we often install a new retainer clip when reconnecting a clip-on fuel supply line or fuel return line. At $2 per retainer clip, this is inexpensive insurance!

After hooking up the fuel supply line, we reinstalled the OEM fuel supply pump fuse. We cleared the DTC (Engine Check) code while heat soaking the injectors and high pressure CP3 pump. Bump-key fuel pump priming quickly charged the fuel supply. We started the engine and checked for leaks before making a highway run at heavier throttle. This purged debris and completed the pump, injector and upper cylinder cleaning process.

Caution: To protect the CP3 pump, Bosch injectors and fuel valves, we change the OEM fuel filter at regular intervals!

Our 2005 Ram 3500 4WD pickup truck has racked up 179,000 miles on its original common rail electronically-actuated fuel injectors, CP3 high pressure pump, Holset turbocharger and the factory fuel supply system. All parts, including the in-tank fuel pump, are original.

Note: Our Ram 3500 receives regular care. To date, the only service parts needed for the injection and induction systems have been quality (Mopar®/Cummins or Fleetguard) air and fuel filters. We perform regular preventive maintenance, including fluid changes, new filters, chassis lubrication, hoses, belts, thermostat and preventive care brake service.

Diesel “Stiction” Footnote: The Ford Powerstroke Issue

The term “stiction” (“static” plus “friction”) has become a diesel fuel injector hot topic. The term refers to the HEUI style injectors used in Ford Powerstroke 7.3L and 6.0L Navistar engines. These injectors use pressurized engine oil and a solenoid motor to open fuel flow to the injector nozzles.

Stiction results from the buildup of gum and sludge, oil breakdown and the varnish created within the pressurized oil components of these injectors. A sticky HEUI injector spool valve or poppet causes poor injector performance and major drivability issues. Ford Powerstroke engines with HEUI injectors have created the stiction phenomenon.

Bosch fuel injectors used in the Cummins 24-valve CRD 5.9L engine do not use pressurized engine oil to initiate fuel flow within the injectors. These injectors reach very high pressures when under heavy throttle load, which requires an iron injector housing, heavy duty solenoid and a spring balanced check ball system. Here is an insightful overview of how Cummins Bosch fuel injectors operate as posted by a YouTube user. Despite the low resolution, this instructional message is insightful:

Insightful overview of a Cummins high pressure injection pump and Bosch fuel injectors. This low resolution instructional video is shared by a YouTube user.

Here is a breakdown of the components within a Bosch diesel fuel injector. Seidel Diesel Group specializes in clean room level Bosch diesel injector rebuilding:

Insight into the components that make up a Bosch diesel fuel injector. Helpful for understanding the precision functions of these injectors…Courtesy of Seidel Diesel Group (SDG).

Ford Powerstroke issues have led to a number of aftermarket fuel and crankcase additives that target stiction. For our Cummins Bosch injectors, cleaning is a matter of keeping the injector check ball, plunger and nozzles clean and working properly. Maintenance with these Cummins Bosch injectors is strictly a fuel system issue. Clean, well-filtered fuel and periodic CP3 pump and injector flushing with Sea Foam Motor Treatment and our S.U.R.&R. FIC203 Injection Cleaner Kit is part of our preventive maintenance.

Stiction in the Powerstroke HEUI injectors is a real issue and centers around engine oil type and oil additives. Although the two injector cleaning methods demonstrated in this post’s video would clearly benefit the fuel flow side of HEUI injectors, the Ford truck owner’s larger injection concern is engine oil gum, sludge, oil breakdown, static/friction issues and keeping the HEUI oil-pressurized components clean and operating smoothly.

Sea Foam Motor Treatment is a proven oil additive as well as a fuel system cleaner. Sea Foam in the engine crankcase does have benefits for hydraulic lifters, piston rings and likely the HEUI injector oil circuits. The use of the correct engine oil and routine service is critical on Ford Powerstroke engines with HEUI injectors. Sea Foam used as recommended would be beneficial.

For more details on Sea Foam® Motor Treatment and the full line of products visit:


For more details on S.U.R.&R. Tools and other products visit:


For in-depth coverage of the FIC203 Cleaner Kit in action on our Jeep 4.0L gasoline engine, see the 32-minute how-to video at:


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Sean February 17, 2024 - 6:31 am

Seafoam contains alcohol and should not be used in the common rail engines as it can damage the injectors. It probably does clean them but why use something that can possibly do damage. Stick to a pure diesel injector cleaner and you will get the same or better results. Without the possible damage.

Moses Ludel March 2, 2024 - 10:09 am

Sean…Thanks for sharing your concern. In following up on your comments, I reviewed the MSDS Sheet on Sea Foam Motor Treatment, which is recommended for both gasoline and diesel engines as a fuel tank or crankcase oil additive. Sea Foam Motor Treatment does contain isopropanol. The active ingredients listed in the “proprietary mixture” are less than 25% isopropanol (a common fuel additive) and less than 95% hydrocarbon blend. This means there could be as little as 5% isopropanol (with 95% hydrocarbon blend), or as much as 25% isopropanol (with a 75% hydrocarbon blend)—or ratios between these points. Worth noting, these are the only MSDS ingredients listed for the product. Also be aware that I idled the engine with the Sea Foam as fuel for a brief period, did not put the engine under load, and there was no “piston rattle” or indication of detonation…I also looked at a few dedicated “diesel injector cleaner” products. Some of the ingredients that come up include 2-Ethylhexyl Alcohol, 2-ethylhexan-1-ol, Xylene, toluene, Napthalene, 1,2,4-Trimethylbenzene and a variety of naptha and petroleum (stoddard) solvents. Howes at Canada avoids alcohol in its diesel treatment and has a long list of MSDS ingredients: MSDS for Howes’ Diesel Treatment. Any of these products can be highly toxic and should be handled accordingly. Hydrocarbon fumes, ingestion and absorption are an issue with any petroleum product. Industrial or denatured alcohols should never be ingested or absorbed into the bloodstream through a skin cut. Benzene and many other compounds have a history as carcinogens. Consumers should research products, read content and safety labels, look up SDS/MSDS Sheets for details and make informed choices…Moses


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