How to Prime a Diesel Engine

by Editorial Team

The easiest way to prime a diesel engine is to not have air in the fuel line to start with. But if you must do some work on the fuel system, that just isn't possible. Here are the steps to prime a diesel engine in case you find yourself needing to do this difficult task.

Step 1

Get a good mechanic's repair manual. This will give you all the specific details for your diesel engine. These manuals also generally give you a list of tools you need to work on your diesel engine as well.

Step 2

Look the fuel system over and check for any obvious air leaks. Fill with clean fuel to do this.

Step 3

Fill your fuel filters with clean diesel and replace them. Do one fuel filter at a time.

Step 4

Take off the primer handle from the injector pump and pump it until you get fuel pressure on the system. Be patient, this can take hundreds of pumps until you get pressure back on the system.

Step 5

Put the primer handle back on the injector pump and on the fuel filter assembly. Open the bleeder screw slightly to check for air.

Step 6

Repeat Steps 4 and 5 until you can no longer see air coming out. At this point you should see pressure at the primer pump after about five pumps.

Step 7

Reassemble and turn on the engine. It may run a little rough until the fuel is completely free of air.

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