The Cummins turbo-diesel is a popular light-duty diesel engine that was available in the Dodge Ram, as well as in some commercial vehicles and motor homes. If your Cummins diesel runs out of fuel, or if you have changed the fuel filter, air will enter the Cummins fueling system, requiring air to be purged from the system for it to function properly. Air in the system can manifest itself in very difficult starting, poor idling, and exhaust smoke. Earlier model Cummins turbodiesels require a manual bleed, while later Cummins diesels have an automatic bleed procedure.
Step 1: how to bleed a cummins engine
Make sure the truck engine is cool before bleeding the system. If your Cummins is a 1997 or earlier model, there is a manual primer located on the lift pump, which is located under the fuel filter on the driver’s side of the engine block. It will be a tab that you can work from one side to the other.
Step 2: how to bleed a diesel engine
Open the bleed screw on the fuel filter and pump the hand primer until fuel comes out of the bleed screw. Pick up spilled fuel with rags or a small bucket. When you notice that there are no air bubbles in the fuel, close the bleed screw. You may want to perform this procedure several times over the course of a few days to purge all air from the system.
Turn the ignition to the “On” position and allow the electric lift pump to cycle if your Cummins is on a 1998 or later model. When the key is turned to the “On” position, the lift pump will cycle for approximately 30 seconds, during which the system will refill the fuel tank. Repeat this process three times to purge as much air as possible from the system.
Tip, how to bleed a cummins diesel engine
- Filling a fuel filter with diesel fuel before installation can reduce the amount of air that will need to be purged from the system.
Items you will need, such as bleed diesel engine
- Complete set of hand tools including wrenches and socket set
- Rags and a small bucket