Ford F81Z-9C968-AB Fuel Pressure Regulator

It is used only for 7.3L engines because on 6.0L and 6.4L engines the fuel pressure regulator is installed internally to the fuel filter housing. Start by removing the cable from the negative terminal of the battery before then reducing the pressure on the fuel system. To drain the diesel fuel, take out the fuel filter and employ the use of a siphon or suction pump in pumping out all the diesel fuel in the fuel filter/water separator housing. Cutoff both of the fuel supply and return lines from the housing and then cut off both fuel lines from the cylinder heads. Then, remove both the fuel pressure regulator and the fuel heater connector, also, exhaust backpressure sensor electrical connector before you remove the sensor. Remove the two mounting bolts of the fuel filter/water separator and pull up the assembly out of the engine compartment. In the 7.3L engines, removing the fuel filter/water separator housing will release the fuel pressure regulator and turning it in an anti clockwise direction will make it easier to remove it. It is necessary to separate the regulator from the housing; unscrew the cap, O-rings, spring, poppet valve, and the seat of the valve. Don't forget to always clean the fuel pressure regulator bore and carry out the replacement of the O-rings with the new parts before screwing the regulator in place while applying the right torque. For both 6.0L engines, uninstall the engine attached fuel filter and pump the fuel from the canister and dispose it appropriately. Remove the fuel line from the regulator cover of the fuel filter housing, and also remove the four screws of the fuel pressure regulator cover and take it up. Take out the little restrictor on the top of the regulator as well as the spring and poppet in lower section. Deep clean the regulator bore if possible and be gentle to avoid scratches, replace the regulator by undoing the procedure step by step.

EFI models maintain constant fuel pressure from the fuel pressure regulator by causing resistance beyond the injectors, thus allowing some of it to go back to the tank. It can vary its restriction through engine vacuum, a diaphragm, and a spring as engine requirements change. Additionally, when the fuel pump is not running, the restrictor closes very fast and acts like a check valve thereby aiding quick engine restarts. For proper functioning, fuel flow should be unblocked, an open return path must exist along with a dependable vacuum signal. Failure can result in overpressure or underpressure which are caused by contamination or valve malfunctions.