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How to Prime Diesel Tractor Pumps

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Diesel tractor fuel pumps need to be primed whenever the fuel tank has been emptied completely. This includes the tractor’s first fueling, running out of diesel fuel completely during use or after maintenance of the fuel system. Priming ensures that the fuel system of a diesel tractor is free of air pockets, increasing the fuel system’s hydraulic pressure. Without properly priming the diesel fuel system, the risk of stalling your engine when starting your tractor increases greatly.

Prep Work and Self-Priming Systems

Read your model-specific tractor owner’s manual to learn more about priming your diesel tractor pump. Priming instruments and techniques may vary from model to model. Some diesel engines utilize a self-priming system that does not require manual priming.

Fill your tractor’s fuel tank until full.

Turn on your tractor. Let it operate for 10 to 15 seconds while in a neutral gear. If your diesel engine uses a self-priming system, this will prime the fuel pump adequately. Turn off your tractor.

Manual Prime

Open the hood to reveal the fuel tank and diesel fuel delivery system. Refer to your tractor owner's manual for dismantling or hood-opening procedures.

Locate any bleeding screws found in the tubing connecting the fuel tank to the diesel engine. Bleeding screws are commonly found at the filter housing or the injection pump. Loosen these screws. If necessary, use an appropriate screwdriver, or loosen the screws with your hands if they’re covered by screw head grips.

Pump the fuel priming lever with your hand to prime your recently refilled fuel system. Tighten any bleeding screws once the tubing begins to expel pure diesel fuel without air pockets. Continue pumping in this manner until all bleeding screws have been tightened, or follow the guidelines laid out by your owner’s manual.

Turn on your tractor. Let it run for a few moments to ensure that the fuel pump is properly primed.


Do not touch the fuel tank or fuel delivery system while the engine is operating. Keep the fuel tank covered when operating the engine.