A diesel engine is an option for many Dodge vehicles, especially heavy trucks. An eight-cylinder 5.9-liter diesel engine is available for the 2003 Dodge Ram 2500 3/4 ton pickup. This engine uses fuel injection and requires an injection pump to keep the fuel under pressure. The procedure for replacing the diesel injection pump is the same for all full-size Dodge trucks made from 2001 to 2005.
Disconnect the cables from the negative battery terminals with a socket wrench. Remove the throttle linkage and its bracket. Disconnect the fuel drain manifold, and detach the fuel lines from the injection pump. Remove the fuel air control tube and the connector for the fuel shut-off valve from the injection pump. Disconnect the support bracket and oil fill tube from the injector pump.
Put a shop rag over the opening in the injector pump's gear cover. Remove the gear retaining nut and washer for the injector pump with a socket wrench. Turn the crankshaft clockwise with a socket wrench until the top dead center pin on the crankshaft drops into the gear timing hole. Pull the pin from the gear timing hole.
Remove the lock screw and its washer from the injection pump with a socket wrench. Tighten the lock screw to 22 ft. lbs. with a torque wrench, then push the drive gear for the injection pump from the drive shaft. Disconnect the mounting nuts for the injection pump with a socket wrench. Remove the injection pump from the crankcase.
Install the new injection pump and tighten the mounting nuts by hand, ensuring that the pump can move freely within its slots. Connect the drive gear to the drive shaft with its retaining nut and washer. Tighten the nut to between 11 and 15 ft. lbs. with a torque wrench.
Rotate the injection pump counterclockwise to take up gear lash. Tighten its mounting nuts to 18 ft. lbs. with a torque wrench. Connect the support bracket for the injection pump. Tighten the nut for the pump drive gear to 48 ft. lbs.
Connect the oil filler tube and connector valve for the fuel shut-off valve to the injector pump. Attach the fuel lines to the injector pump. Install the fuel drain manifold and throttle linkage with a socket wrench. Connect the cables for the negative battery terminals.
Loosen the bleed bolt on the fuel rail with a socket wrench. Push the primer button on the fuel transfer pump until the fuel coming from the bleed screw no longer has air bubbles. Tighten the bleed screw to 72 in. lbs. with a torque wrench. Start the engine and check for fuel leaks.
