Fuel Pump Module
All models are equipped with an in-tank fuel pump module which includes a fuel strainer, gauge float, gauge sending unit and pump. See Fig 1 or Fig 2 . On Cherokee and Wrangler, fuel filter/fuel pressure regulator is mounted on top of fuel pump module. On Grand Cherokee, fuel filter/pressure regulator is located in front of fuel tank, above rear axle. See Fig 3 .
On all models, turbine-type electric pump is driven by a permanent magnet, 12-volt electric motor. Voltage to operate pump is supplied by PCM through a common ASD relay and fuel pump relay circuit. Fuel is drawn in through a separate filter/strainer at bottom of fuel pump and pushed through fuel filter/pressure regulator to fuel outlet line (to fuel injectors).
Fuel filter/pressure regulator is a mechanical device calibrated to maintain fuel system operating pressure at 44.2-54.2 psi (3.1-3.7 kg/cm2 ) across injector tips. If fuel pressure is more than specified, an internal rubber diaphragm and calibrated springs will move from open to closed position. On Cherokee and Wrangler, excess fuel is returned directly into fuel tank through regulator without using a return line. On Grand Cherokee, excess fuel is returned to fuel tank through a fuel return line. On all models, when fuel pump is not operating, some fuel pressure is maintained by a fuel pump outlet check valve to help with engine start-up.