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How to Replace an injector in Cummins 6.7L Engine

Updated on January 4, 2010
Cummins 6.7L
Cummins 6.7L

Many of you out there don not know to much about the 6.7L Cummins Engine.  Today I am going to tell you how to replace and injector on the 6.7L fuel system. 

First of all prepare your workstation, make sure your tools are ready and easy accessable.  One very important thing make a very clean area to lay parts you are going to remove.  Make sure you stay organized keep it neat, don't just throw parts and bolts anywhere.  Diosconnect the batteries.  Using a 11mm socket remove the clamps on the egr cross over.  Then remove the egr cross over 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 a 8mm socet remove the top cover on the engine to gain access to the front valve cover bolts.  Save and reuse this covers gasket.  Now using a 10mm socket remove the six bolts holding the valve cover down.  Remove the valvecover and set aside.  Now you will have complete access to the rockers and injectors.  Disconnect the injector harness from the main harness and with a 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 dont mix them up so you wont have to set the valved lash later. After you have remove the rockers. Now locate the injector you need to remove.  Remove the high pressure fue 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 a 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. Install injector into the port.  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 a inch pound torque wrench tighten the injector hold down to  First 30 inch lbs Then final tightening at 79 inch lbs.  Now reinstall your the injector connector tube and tighten to 50 ft lbs.  Now install your rockers and torque down them to 27 ft lbs. Reinstall the injector harness and tighten all the nuts on injectors 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. Reinsatll the intake plenum and conn ect the boost tube to the intake plenum.  Now connect all your electrical connections to egr and intake.  Reconnect the connections that run across the valve covers rear.  Reinstall the top cover.  Reinstall the egr cross over tube and tighten clamps.  Now using star scan enter the injector trim code you wrote down that was stamped on new injector.  Donot forget this step engine light will stay on if there is wrong code entered. Now clear codes from unplugging sensors and your done.  Test drive the truck to ensure proper operation.


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