1.Make sure the
vehicle has some fuel in the tank. If in doubt, add a few gallons
and again try starting the vehicle before proceeding.
2.Check the vehicle's on-board diagnostic system for any fault
codes. These should be corrected before diagnosing the fuel
3.Using a wiring diagram and voltmeter, check specific voltage
at pump relay, fuse, inertia switch. oil-pressure switch and
4.If the pump is receiving the correct voltage, turn key on.
Pump should start and run from two to four seconds.
5.If the vehicle runs, but is hard to start, install a pressure
gauge by teeing into the fuel line (TBI) or using the service
fitting on the fuel rail (EFI). Turn the key on and check the
gauge to make sure that the pressure does not drop more than
10% of its maximum reading. If adequate pressure is not maintained,
the check-valve is stuck. Replace the fuel-pump assembly.
6.Start the vehicle and check fuel-system pressure with the
gauge still hooked up. If system pressure is too high, it may
indicate a defective pressure regulator, a kinked or broken
vacuum line, or a blocked return line.
7.If the fuel-system pressure is too low, it may indicate a
leaking pressure regulator, a clogged fuel-pickup strainer,
or a blocked fuel-line filter.
Removing the Fuel Tank
When the in-tank fuel pump is identified as the problem component,
the fuel tank must be removed or lowered enough for access to
the pump hanger assembly. (Refer to vehicle repair manual.)
Before servicing, please review the safety precautions 1 and
prepare the work area for the cleanliness requirements.
1.First, release tank pressure by removing the filler cap. Then
relieve fuel system pressure by removing the pump fuse and running
the engine until it quits from fuel starvation. Crank engine
briefly to confirm pressure relief. NOTE: Some systems have
two fuel pumps: low-pressure in-tank, and high-pressure in-line.
Be sure to disable both fuel pumps when this applies.
2.WARNING: Gasoline vapors are explosive! To reduce the possibility
of sparking, disable the electrical system by disconnecting
the negative (-) battery cable.
3.Drain fuel to lighten the tank and avoid spilling when removing
the pump hanger assembly. Use only an approved container, preferably
one that filters the fuel for reuse in the vehicle.
4.Remove the fasteners for the fuel filler neck, noting their
different sizes and locations, then raise vehicle on the hoist.
(If working without a hoist, use an approved floor jack to raise
the vehicle and approved jack stands to support it.)
5.Support the tank with a transmission stand or floor jack.
Note location of fuel outlet, fuel return and vapor return lines.
Remove the lines, using a clean shop towel to absorb draining
fuel, and inspect them for cracking or chafing. When replacing
high-pressure lines, use only SAE R-7 hoses or higher. Disconnect
pump wiring harness.
6.Remove tank straps, and filler neck tube if necessary. Lower
tank enough to access fuel pump hanger assembly, or completely
remove tank.If tank is rusted inside, or seriously damaged,
it must be repaired or replaced before proceeding. Also replace
hangers that show excessive rust, wear or damage. Do not return
sour or contaminated fuel to the vehicle. Dispose of properly.