Alliant AP63401 IPR Valve

Injection Pressure Regulator (IPR) Valve is located in the valley on the High Pressure Oil Pump (HPOP). These can stick, seals get damaged, have the sensor go bad or the wires get damaged. Locate the IPR Valve, check for loose or damaged wires, check that the tin nut on the back of the IPR sensor is tight. When reinstalling the IPR unit torque the IPR to 35ft/lbs and do not use sealer on the IPR threads, as there is an orifice in the threaded area which the sealer could plug.