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How to Replace an Injector in the Cummins 6.7L Engine

Cummins 6.7L

Cummins 6.7L

The 6.7L Cummins Engine

Many of you out there do not know too much about the 6.7L Cummins Engine. Today, I am going to tell you how to replace an injector in the 6.7L fuel system.

Before you start, prepare your workstation. Make sure your tools are ready and easily accessible. One very important thing: make a very clean area to lay the parts you are going to remove. Make sure you stay organized and keep it neat; don't just throw parts and bolts anywhere.

  • Disconnect the batteries.
  • Using an 11mm socket remove the clamps on the EGR crossover.
  • Then remove the EGR crossover tube. Unplug the connections to the EGR valve and the connections to the intake flow valve.
  • Remove the boost tube from the intake plenum. Remove the first high-pressure fuel line from the connector tube and the HPCR. Using a 10mm socket, remove all the intake plenum bolts and remove the intake. Now you have more room to get to fuel lines and rail.
  • Now, with an 8mm socket, remove the top cover on the engine to gain access to the front valve cover bolts. Save and reuse this cover gasket.
  • Now, using a 10mm socket, remove the six bolts holding the valve cover down. Remove the valve cover and set it aside. Now you will have complete access to the rockers and injectors.
  • Disconnect the injector harness from the main harness and, with an 8mm socket, remove the harness from the injector solenoids. Notice the injector harness doubles as the valve cover gasket. DO NOT DISCARD!
  • Depending on which injector you will be removing, you need to remove the exhaust rockers on each cylinder to access the injector hold-down bolts. Remember to put the rockers in order; don't mix them up so you won't have to set the valved lash later.
  • After you have removed the rockers, now locate the injector you need to remove. Remove the high-pressure fuel line from the HPCR and the connector tube to the injector with a 19mm.
  • Now remove the connector tube hold-down using a 24mm. Some connector hold downs are hard to get to; use a swivel if needed. Set the hold down aside.
  • Using an 8-mm socket remove the injector hold down bolts.
  • Pry up on the injector by using a clean well-placed pry bar. There are several grooves in the injector that are suitable for this. There is not a lot of force needed to "pop" them out.
  • Remove the injector. Then remove the injector hold down from the injector because it will be used on the new injector.
  • Remove the new injector from the packaging and be as clean as possible.
  • Install the injector hold down on the new injector. Notice the groove in the rocker seat next to the injector hole. This is where the round part of the injector clamp will go; remember, the injector can only go into the clamp one way.
  • Write down the injector code so you can write it into the engine computer at the end.
  • Pay attention to the rounded and square collar on the injector clamp; the round side goes next to the rocker seat. Insert the injector and clamp into the port. Place a rag over the top of the injector and use some pressure to "pop" the injector down into its seat, you will hear and feel a definite "click" when it goes in.
  • Now with an inch-pound torque wrench, tighten the injector hold down to the first 30 inch-lbs, then do final tightening to 79 inch-lbs.
  • Now reinstall the injector connector tube and tighten it to 50 ft-lbs.
  • Install your rockers and torque down them to 27 ft-lbs.
  • Reinstall the injector harness and tighten all the nuts on the injector solenoids.
  • Reconnect the main harness to the injector harness.
  • Depending on how many injectors you have to replace, reinstall fuel supply lines starting with number 6 and working forward. Note that number 4 crosses over number 5 onto the fuel rail. Tighten the fittings.
  • Reinstall the intake plenum and connect the boost tube to the intake plenum. Now connect all your electrical connections to the EGR and intake.
  • Reconnect the connections that run across the valve cover's rear.
  • Reinstall the top cover. Reinstall the EGR crossover tube and tighten the clamps.
  • Now, using star scan, enter the injector trim code you wrote down that was stamped on the new injector. Do not forget this step; the engine light will stay on if the wrong is code entered.
  • Now clear codes from unplugging sensors and you're done. Test-drive the truck to ensure proper operation.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.