The fuel pump is a high pressure electric one equipped in the
Fuel Tank, impeller works as the vapor preventer and pre-charges high pressure assembly. Fuel is delivered at positive pressure through an in line fuel filter to the
Fuel Rail assembly, the pressure regulator keeps the pressure required by injectors and any excess fuel is returned to the fuel tank through fuel return line. The electric pump connected in parallel with the PCM and operates whenever the ignition is 'on' and the engine is cranking or running; it turns off immediately the engine cuts or the starter is removed within one second. To remove and install on 4.5L and 4.9L engines, turn off the ignition, disconnect the negative battery terminal, discharge the fuel system, lift the front part of the vehicle and then un bolt the fuel tank, to get access to the pump, turn counter clockwise the cam lock ring to lift the assembly out. To remove it, one has to pull the pump up and at the same time pull it outwards taking care not to break the rubber insulator or the strainer which is always stuck beside it. Installation requires removal of all damaged hoses, forcing the pump into the hoses, employing a brand new O-ring seal, and checking the strainer does not encumber the float arm. For the 4.6L engine, there is integrated fuel sender assembly, which contains fuel pump; it is very difficult to repair due to the use of special tools. Do not fill the tank to the full whenever you want to access the sender with a view of avoiding spilling of fuel. Once you have taken off the fuel rail pressure and has disconnected the battery, then try to find out whether the tank needs to be dropped or whether the access is possible at the rear. If possible, lower the tank, and take off the spare tire lid and rear emblem, unbolt quick connect hoses and electrical plugs, spanner wrench for the ring. Upon removal the sender assembly must be tilted slightly in order to avoid sending the floats out of alignment. Remove the strainer and O-ring and before fitting the new one ensure that the strainer does not hinder the float arm from moving. Reinstalling the battery require checking for any form of leaking during the cycling of the ignition and at the same tightening the access panel bolts. The in-tank pump works when the ignition is on and will remain on during any engine running or cranking, and it will shut down should it fail to detect any reference pulses.