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This article is on how to disassemble a Cummins 24v VP44 injector and thoroughly clean and then reassemble it.For starters, you need to refer back to injector removal and get all 6 Injectors removed from the engine. Once you got all six injectors out you can proceed to clean each injector. But something to be aware of there is small parts and these parts must be put back exactly the way it came apart. WARNING! Only disassemble and clean only 1 injector at a time. All the parts are tuned to that particular body. Don't mix and match parts! Then before you can remove the nut you need to remove your copper washer. This can be done with a putty knife and a hammer just lightly tap the putty knife and it should be able to pry it up enough to using the putty knife or a screwdriver. Now as I set my torque wrench for loosening and kept adding torque to the handle adjustment looking for the click and loosening of the nut. I found it at about 32 foot/pounds so I backed off to 30 foot/pounds and set the wrench. Loosen the nut. Now you need a clean area too. I set up a shop towel and an old ashtray. I filled the ashtray with Coleman fuel (Naphtha). So I would open up the injector carefully and place all the parts in the solvent to soak. Now in the picture above there is a shim that goes in the bottom below the spring. This shim might be stuck inside the body don't sweat it let in soak in the Coleman fuel for about 5 minutes and pick it up and it will fall out. Now that all the parts are soaking take an old scotch bright one that's been used a bit and rather soft. dip it in the solvent and light rub the nozzle clean of soot. Yes, you may rub the tip but be gentle about it. Now look at the pintle (needle) look at the tip for damage or wear... Now check it for smooth sliding action in the nozzle. If it feels rough rub the pintle gently with the scotch bright pad and it will help it out... I was doing a mini-spray test too... Dip the nozzle in the solvent keeping the fuel hole up and holding the nozzle horizontal using a blow gun just a light burst of air will show you your spray pattern somewhat but also ensures the nozzle tip is not plugged. Now just blow all the large parts clean and dry from the solvent. Make sure to blow the fuel passages clear. Once you happy with the clean up and every is clean now reassembly the injector exactly the way it came apart. Put your shim in the body take notice of which side was up. You'll also notice the shim has worn marks from the spring so be sure to put it back in the right way. The shim has to be this side up... Take notice to the side that has the wear mark for the spring... Then place your spring the body. Then there is a cone shaped piece that goes on top of the spring but make sure to place the hollow side up. This is for the pintle to ride in. The mid body goes on top of this take notice to the pins it will only go on one way... Then your nozzle and pintle go on top to look like this... Here is a good video of how I did each injector.

Fuel Injector Operation High-pressure fuel is supplied from the Bosch VP44 injection pump, through a high-pressure fuel line, through a steel connector, and into the fuel injector. When fuel pressure rises to approximately 31,026 kPa (4,500 psi), the needle valve spring tension is overcome. The needle valve rises and fuel flows through the spray holes in the injector nozzle tip into the combustion chamber. The pressure required to lift the needle valve is the nozzle opening pressure. This is sometimes referred to as the “pop” pressure setting. Each fuel injector is connected to each high-pressure fuel line with a steel connector. This steel connector is positioned into the cylinder head and sealed with an o-ring. The connectors are sealed to the high-pressure fuel lines with fittings. The ferrule on the end of the high-pressure fuel line pushes against the steel connector when the fuel line fitting is torqued into the cylinder head. This torquing force provides a sealing pressure between both the fuel line to the connector and the fuel connector-to-fuel injector. The fitting torque is very critical. If the fitting is under-torqued, the mating surfaces will not seal and a high-pressure fuel leak will result. If the fitting is over torqued, the connector and injector will deform and also cause a high-pressure fuel leak. This leak will be inside the cylinder head and will not be visible. The result will be a possible fuel injector miss-fire and low power. The fuel injectors use hole-type nozzles. High-pressure flows into the side of the injector and causes the injector needle to lift and fuel to be injected. The clearances in the nozzle bore are extremely small and any sort of dirt or contaminants will cause the injector to stick. Because of this, it is very important to do a thorough cleaning of any lines before opening up any fuel system component. Always cover or cap any open fuel connections before a fuel system repair is performed. Each fuel injector connector tube contains an edge filter that breaks up small contaminants that enter the injector. The edge filter uses the injectors pulsating high pressure to break up most particles so they are small enough to pass through the injector. The edge filters are not a substitute for proper cleaning and covering of all fuel system components during repair. The bottom of each fuel injector is sealed to the cylinder head with a 1.5mm thick copper shims (gasket). The correct thickness shim must always be re-installed after removing an injector. Fuel pressure in the injector circuit decreases after injection. The injector needle valve is immediately closed by the needle valve spring and fuel flow into the combustion chamber is stopped. Exhaust gasses are prevented from entering the injector nozzle by the needle valve. Fuel Injector Removal The fuel injectors are located in the top of the cylinder head between the intake/exhaust valves. 1. Disconnect both negative battery cables from both batteries. Cover and isolate end of cables. Each fuel injector is connected to each high-pressure fuel line with a steel connector tube. This steel connector is positioned into the cylinder head and sealed with an o-ring. The connectors are connected to high-pressure fuel lines with fittings. 2. If injector at #1 or #2 cylinder is being removed, intake manifold air heater assembly must be removed. 3. If injector at #5 cylinder is being removed, remove engine lifting bracket (2 bolts). 4. Thoroughly clean area around injector and injector high-pressure lines before removal. 5. Remove necessary high-pressure fuel lines. (Refer to - Injection Lines). Do not bend any high-pressure fuel line to gain access to the fuel injector. Cover or cap any open fuel connections. 6. Remove valve cover. Mopar's Notes Most of us will be doing full injector upgrades or replacements. So I know the service manual talks as if replacing 1 or 2 injectors. I highly suggest you remove every as pictured below. APPS Sensor - Removal. Leave the throttle cable attached and lay on the PDC box. Remove the intake and grid heaters by pulling the 4 bolts and the band clamp. Lay the intake and grid heater aside on the PDC box. Remove the valve cover. Remove the injection lines 7. Thread Special Tool 8324 (Fuel Injector Connector Tube Remover) onto the end of injector connector tube. Mopar's Notes You can use a small flat blade screwdriver. Just hook one of the threads on the connector tube and lightly pry out. WARNING! Be aware and not scratch the mating surface of where the tube and high-pressure line and the connector tube meet if you do there will be a fuel leak. 8. Pull injector connector tube from the cylinder head. The injector connector tube must be removed before attempting to remove fuel injector or serious damage to fuel injector and tube will result. 9. Remove and discard old o-ring from injector connector tube. 10. Remove fuel injector hold down clamp bolt at the front end of the clamp. Do not loosen or remove special (2 shouldered) bolt at the rear end of the clamp. Remove injector clamp by sliding it from shoulders on rear clamp bolt. 11. Thread rod from Special Tool number 8318 (Fuel Injector Remover) into the top of the fuel injector. Mopar's Notes Take one of your short intake bolts and thread it into the head of the injector. 12. Tighten nut on 8318 tool to pull (remove) fuel injector from the cylinder head. Mopar's Notes Use a screwdriver and pry the injector straight up carefully. 13. Remove and discard old o-ring from the fuel injector. 14. Remove and discard copper sealing washer (shim) from the bottom of the injector. If copper sealing washer has remained in the cylinder head, it must be removed. Fuel Injector Installation The fuel injectors are located in the top of the cylinder head between the intake/exhaust valves. 1. Inspect fuel injector. a. If necessary, perform a pressure test of the injector. b. Look for burrs on injector inlet. c. Check nozzle holes for hole erosion or plugging. d. Inspect end of the nozzle for burrs or rough machine marks. e. Look for cracks at the nozzle end. f. Check nozzle color for signs of overheating. Overheating will cause the nozzle to turn a dark yellow/ tan or blue (depending on overheating temperature). g. If any of these conditions occur, replace the injector. 2. Thoroughly clean fuel injector cylinder head bore with special Cummins wire brush tool or equivalent. Blow out bore hole with compressed air. 3. The bottom of the fuel injector is sealed to cylinder head bore with a copper sealing washer (shim) of a certain thickness. A new shim with correct thickness must always be re-installed after removing injector. Measure thickness of injector shim. Shim Thickness: 1.5 mm (.060”) 4. Install new shim (washer) to the bottom of the injector. Apply a light coating of clean engine oil to the washer. This will keep washer in place during installation. 5. Install new o-ring to fuel injector. Apply a small amount of clean engine oil to o-ring. 6. Note fuel inlet hole on the side of the fuel injector. This hole must be positioned towards injector connector tube. Position injector into cylinder head bore being extremely careful not to allow injector tip to touch sides of the bore. Press fuel injector into cylinder head with finger pressure only. Do not use any tools to press fuel injector into position. Damage to machined surfaces may result. 7. Position fuel injector hold down clamp into shouldered bolt while aligning slot in the top of the injector into the groove in the bottom of the clamp. Tighten opposite clamp bolt to 10 N·m (89 in. lbs.) torque. 8. Install new o-ring to fuel injector connector tube. Apply a small amount of clean engine oil to o-ring. 9. Press injector connector tube into cylinder head with finger pressure only. Do not use any tools to press tube into position. Damage to machined surfaces may result. 10. Connect high-pressure fuel lines. Refer to High-Pressure Fuel Lines Removal/Installation. The fuel line fitting torque is very critical. If the fitting is under-torqued, the mating surfaces will not seal and a high-pressure fuel leak will result. If the fitting is over torqued, the connector and injector will deform and also cause a high-pressure fuel leak. This leak will be inside cylinder head and will not be visible resulting in a possible fuel injector miss and low power. (28 ft. lbs.) 11. Install valve cover. 12. (If necessary) install intake manifold air heater assembly. Refer to Intake Manifold Air Heater Removal/Installation. 13. (If necessary) install engine lifting bracket. Tighten 2 bolts to 77 N·m (57 ft. lbs.) torque. 14. Connect negative battery cables to both batteries. 15. Bleed air from high-pressure lines. Refer to Reprime fuel system procedure.