'98 V-6 Fuel Pump Replacement

Discussion in 'SN95 V6 Mustang Tech' started by Mhudick, Sep 1, 2006.

  1. 1998 Mustang Fuel Pump Replacement

    Tools needed:

    • Fuel line removal kit (Kragen’s for about $14). These are sleeves which slip over the fuel line and then release the springs that hold the two ends together.
    • Sockets
    o 6mm to 13 mm.
    o Lug nut
    • Torque Wrench
    • Extensions for sockets
    • Ratchet
    • Soldering Iron
    • Needle nose pliers
    • Assortment of socket drivers for sheet metal screws
    • Assortment of flat blade screw drivers
    • 12 Volt continuity light (find at an auto parts store, or Radio Shack)
    • Soldering iron if soldering connections instead of using crimp on connectors
    • Fuel container(s)
    • Siphon Hose
    • Compressed air
    • Air gun ( Use to create vacuum in hose to start siphoning gas)

    Parts needed:

    • New Fuel pump ($79 + Shipping costs from Reno, Nevada – Available from “efuelpumps.com”).
    o Note, if you are capable of removing the old pump assembly, you are capable of replacing just the pump. You do not have to endure the extra expense of buying the entire assembly, which is reusable.
    • Fuel Filter (Kragens ~$12)
    • Solder-less connectors (any Auto Parts store)
    • Solder if you prefer (as I do)
    • Shrink wrap for exposed wire connections ( Radio Shack)


    My OEM pump failed at 8 years and 60,000 miles. It worked fine until I stopped the engine to pick up my mail, then nothing when I tried to restart. The source of the problem wasn’t obvious to me, though I have maintained my own and others’ cars for years.

    Trouble shooting:

    • Is there pressurized fuel available?
    o On the right side of the engine is the Chrome plated fuel line rail, which has a bicycle type valve hidden under a black plastic cap. Remove the cap and depress the valve with a small tool and see if gas squirts out. If it does, then the pump is probably not the problem. If no fuel, then it could be the pump malfunctioning, the relay, the ignition switch or the inertial cutout switch (fuel injected cars) which is located in the trunk, left rear side.

    • Does the pump whirr when the ignition is first switched on?
    o Turn on the ignition without trying to start the car. The fuel pump should whirr for about two seconds, after which time the computer shuts it down. Listen for the sound, which is easy to hear if you are listening at the tank, or with your ear in the trunk.

    o If no whirr, check the inertial cut out switch, which is located in the trunk, mounted to the left rear vertical wall, behind the tail lights. There is a button at the top. If the button has popped out, it can be reset by pushing it in. The pump should work if that was the problem.

    • If the switch was not the problem, remove the switch to enable a check for power.

    o Remove the trunk liners to get to it. It is best to remove the plastic trim surrounding the trunk latch at the center of the rear of the trunk. This is held in place by several push in plastic dowels which are hard as hell to remove. A putty knife with a “U” channel cut into it makes the removal easier, but two flat blade screw drivers can work too. Protect the plastic with some masking tape.
    o Then remove the left side covering to expose the switch.

    • Power Check:
    o Using a 12 volt continuity light, check for voltage on both sides of the switch (actually, the check is made at the plug terminals) when the ignition is turned on. Make sure that a good ground is secured. This can be done by connecting to one of the sheet metal screws that hold the switch in place. Any doubt can be eliminated with an OHM meter (Kragens or Radio Shack)
     If the relay is working properly, the light will turn on for two seconds.
     If the relay is not working, the light will not work.
    • I have no idea where the relay is located.
    • The pump can be “hot wired” at the switch plug to make the pump work
    o If a “Hot Wire” does not work, most likely, the pump is bad.
     If the light works on one side of the switch, but not the other side, the switch is no good.
    • Jumping the switch with a short jumper should make the pump run when the ignition is turned on.
    • Assuming the fuel pump is bad.
    o The fuel will have to be removed from the tank.
     Jack up the rear of the car, place on jack stands and remove the right rear wheel to get the room you need to work.
    • If the tank is full, the front of the car may have to be raised higher than the back in order to prevent fuel leaking when the fuel lines are separated at the filter.
     Remove the fuel line from the output of the filter (the input is the end of the filter facing the right rear wheel) and attach a hose to the filter output pipe.
     Cut a slit in the siphon hose, about 2 inches from the output end
     Insert the tapered nozzle of the air gun into the slit and blow air in the direction of the expected fuel flow (into the container). This will create a vacuum between the fuel filter and the air gun nozzle, and as a result, suck fuel out of the tank.
    • To get the maximum amount of fuel out of the tank, the car should be level on the ground.
    o At this point, all the hoses, pipes and electrical connections will have to be separated from the tank.
     Start with the fuel filler pipe
    • There are three sheet metal screws accessible under the filler lid.
    o Remove these.
    • There are three more sheet metal screws holding the rubber gasket that seals the filler pipe where it goes through the trunk.
    o Remove these.
     To access these screws, it is necessary to peel back the trunk trim at the right rear.
    • There is also a rubber gasket between the fuel filler pipe and the outside of the car, accessed from inside the trunk.
    o This gasket prevents gas from entering the trunk during fuel fills. It is adhesively attached, but may tear or move during removal or installation. Use care both ways.
    • There are two venting hoses attached to the filer pipe, accessed from underneath the car. One is simply pushed-on, the other is removed by unscrewing the hose clamp.
    o Remove both
     There is a black plastic vent hose attached to a round black canister, which itself is firmly attached to the top left side of the fuel tank. This hose connects to the underside of the car body.
    • It must be separated from the car body before proceeding.
    o The couple for the end of this pipe is secured to the body end with a one piece white plastic retainer.
     The small end of this retainer is squeezed enough to enable it to be pushed towards the left side of the car
    • While squeezing the retainer, push the black plastic hose towards the left side of the car until it separates.
     Separate the input pipe from the fuel filter, and remove (Replace on assembly) the fuel filter.
    • Wrap the ends of the pipes separated from the filter to prevent dirt from entering the fuel system.
     Separate the fuel line which returns fuel to the tank from the pressure regulator.
     Unplug the electrical connector, located near the right rear top of the fuel tank.
    • The connector is attached to the body with a push-in plastic plug and may be removed to facilitate separation..
     Support the tank with a jack.
    • Use a long board and some cushion material to prevent damage to the tank
     Remove the three 13 mm bolts securing the straps to the body.
     Lower the tank about 8 inches and then inspect to insure that nothing has been forgotten (by either you or me).
    • The fuel filler pipe will still be attached to the tank and it must be removed before the tank can be fully separated from the vehicle.
    o To make this easier, it is best to support the right side of the tank and then lower the left side enough to allow the tank to be pushed to the left far enough (about 8 inches) to remove the filler pipe.
     This is not easy. It must be muscled out.
     At this point, check to see if there is any fuel left in the tank. If there is, this is a good time to remove as much as possible through the fuel filler opening, which can be made larger by removing the O-ring seal (reusable).
    o Fuel Pump Assembly removal.
     The wires are secured in depressions in the tank, under the foam covering the top of the tank. Separate the wiring harness from the tank, unplugging one end from a sensor attached to the top right of the tank (note that this should have been done already).
     Clean the top of the tank and pump assembly flange to prevent dirt from entering the tank
     Remove the bolts that hold the assembly to the tank.
     Gently lift the flange.
     Note that there are several plastic hoses and a wiring harness that attach the flange to the interior pump sub-assembly.
     The hoses need to be carefully repositioned to enable them to be moved from inside to outside the tank.
     The pump sub-assembly on the 1998 Mustang is encased in a white plastic canister that is secured (by two plastic vertical ears) to a plastic retainer attached to the bottom of the tank.
    • The cylindrical retainer (a shell) attached to the tank bottom:
    o It has holes and slots to allow access for the fuel level float and filter of the pump sub-assembly
    o The pump sub-assembly is attached to this retainer by two ears that are squeezed (by hand) together, while lifting up.
     The manual I have for the 1998 states that there is a locking ring holding these two together, so be forewarned if you have something else.
    • Lift the pump sub-assembly and sender far enough to enable the sender float lever arm to be separated from the sender’s plastic retainer.
    o I couldn’t find a way to remove the unit with the float attached to the sender.
     This can be accomplished by using a small flat blade screw driver.
    o With the float out of the way, the pump sub-assembly can be removed by rotating it enough to clear the tank filter (which is replaced with the new pump)
    • Unscrew the sheet metal screw which holds the fuel level sender and remove it from the sub-assembly canister.
    • Remove the two sheet metal screws which secure the fuel lines to the pump.
    • Remove the three sheet metal screws that secure the cover to the canister.
    • Unplug and withdraw the pump.
    • Note that if an entire pump assembly were purchased, removal would have been completed after the sub-assembly had been removed.

    o Replacement of Fuel Pump Assembly
     First assemble the fuel pump sub-assembly
    • Check to insure that the electrical plug fits to the pump.
    • If it does, the wired plug assembly equipped with the replacement pump can be discarded.
    • If it does not fit, then the plug supplied with the pump must be wired in.
    o One has the choice of using crimp on connectors or soldered wires. I chose the later because crimp-on connections are nowhere near as reliable as properly soldered connections.
     Use shrink tubing to insulate the soldered wires
    o Observe proper polarity, which is indicated on the pump (black wire to black wire, and colored wire to colored wire). A miswired connector makes the pump run backwards, which you will discover after you get everything together and the car pumps no gas (pump runs, but car will not fire up).
    • Remove the black rubber boot from the old pump and place it on the new pump. ( After the filter has been removed)
    • There are two filters supplied with the new pump from efuelpumps. One or more may have metal tension rings to secure the filters to their respective mates.
    o Place the smaller one on the pump
    o Place the larger one on the outside of the sub-assembly canister.
    • Note that there is also a small round screen on the bottom of the outside of the plastic canister. It is held in place by retainers cast into the canister base and is easily dislodged.
    • Insert the new pump into the canister
    • Replace the cover and secure it and the hose retainer with the 5 sheet metal screws.
    o The screws should bottom and close the seam line.
     Do not overtighten!
     Second, insert the fuel pump sub-assembly into the tank
    • Note that the filter attached to the outside of the canister can be bent so as to better clear the edge of the opening.
    o This little trick may be how the factory gets the pump into the tank with the float pre- installed.
    • Unless a way is found to insert the subassembly into the tank with the fuel level float attached, it will have to be attached after the sub-assembly is partially inserted into the tank.
    o This is not necessarily a slam dunk
     First, the end of the float lever arm has to be inserted into the hole in the sender (it needs to be aligned with the housing, so rehearse this while it is outside the tank).
     Then the lever arm needs to be squeezed into a fork (looks like a small pickle fork, with a round hole in it) attached to the rotating part of the sender.
    • Accomplish this with a set of needle nose pliers, one prong of which is inserted into a hole in plastic fork and the other on the outside of the lever arm.
    o If you try to simply push the arm into the plastic fork, you may find that you damage the sender.
    • Finish lowering the subassembly into the plastic tank retainer and push until the retainers click into place.
    • Insure that the flange gasket is reusable.
    • Rearrange the flexible fuel lines and wires so they clear the flange without crimpling them.
    • Bolt the flange to the tank.

    • Reinstallation of the tank and fuel lines
     Using double sided tape (like rug tape), secure the wiring to the tank in the depressions provided.
     Using double sided tape, secure the foam over the wiring
     Lube the tank filler pipe with engine oil and slide it into the tank.
     Raise the tank sufficiently to allow reattachment of the filler pipe to the car body.
     Make sure the rubber gasket is good enough to seal the trunk from fuel spills during fill-ups.
     Finish the job by reversing the removal steps.
     Put a gallon of fuel into the tank and check the system for leaks before firing up the engine. It is always possible to forget to reattach one fuel hose.
    • And please remember to plug in the inertial switch if it was disconnected as ab
  2. Checking/Changing fuel pump in 98 Stang

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