Fuel Pump Ford LTD Crown Victoria I

COMPONENT TESTING

Note. Specific component testing information not available. Refer to any tests performed during REMOVAL & INSTALLATION or OVERHAUL procedures

DESCRIPTION

All fuel pumps will be either the mechanical or electrically operated design. Most carburetted vehicles use an engine-mounted mechanical pump.

Gasoline engine vehicles with fuel injection use an electric fuel pump to supply higher pressure demands required with these systems. Electric fuel pumps are normally located in or near the fuel tank. Some models use a low pressure and a high pressure electric pump. Generally, one pump will be located in the fuel tank, and the other externally. This provides adequate fuel delivery during high demand maneuvers and on steep inclines when the fuel tank is near empty.

When trouble shooting fuel pumps, remember that electric fuel pumps do not operate unless a reference signal is received from the distributor. Verify that the unit has enough pressure, volume, and vacuum (suction). When found defective, it is recommended that the fuel pump be replaced as an assembly.

INSPECTION & TESTING

If a malfunction is diagnosed as fuel system related, perform the following tests and inspections prior to replacing fuel pump.

FUEL LINES & HOSES

Inspect all metal fuel lines for damage caused by vibration, impact, or kinking. Inspect rubber hoses for cracks, kinks, or deterioration. If fuel line between engine and fuel tank is suspected of being clogged, disconnect at engine and fuel tank and blow clear with compressed air. NEVER use compressed air on a fuel line unless the line is disconnected at both ends.

FILTERS & SCREENS

Clean or replace all filters and screens located in the fuel line circuitry. Inspect carburetor/throttle body assembly for filters or screens and clean or replace as necessary. In some cases, fuel tank pick-up screen can be clogged enough to affect fuel delivery at high speed.

WIRING CONNECTIONS

Inspect all wires and electrical connections for breaks, loose connections and corrosion. Faulty fuel pump wiring or connections can cause inaccurate testing and diagnosis results.

Mechanical

1. Check fuel supply to verify sufficient gasoline in the tank. Disconnect ignition wire from distributor so that engine will not start.
2. Separate fuel line at carburetor inlet fitting. Install a piece of fuel resistant hose over the end of fuel line. Place end of hose into a gasoline container.
3. Crank engine to activate fuel pump. The amount of fuel pumped will vary according to each manufacturer. The average pump output should be about one pint in 30 seconds.
4. If little or no gasoline flows from hose, check fuel lines or gasoline tank filter for restrictions or leaks. If lines and filter are clear, pump is defective and must be replaced.

Electrical

Note. The following is only a general procedure. For specific manufacturer's electric fuel pump testing procedures, see FUEL INJECTION article in this section.

1. Most vehicles use a fitting to allow pressure test without separating fuel lines. If not, separate fuel line from injector inlet "T". Install a "T" connector with a pressure gauge in the line and reconnect line to injector.
2. Hold pressure gauge about 16" (406 mm) above fuel pump. Pinch off fuel return line (if equipped) using care not to damage hose. Start engine and observe pressure.
3. After pressure check, reconnect steel line. If pressure is not within specifications or varies greatly, replace fuel pump.

1. Disconnect fuel line from carburetor. Connect line to a pressure gauge. Hold gauge about 16" (406 mm) above pump level. Pinch off fuel return line (if equipped).
2. Start engine and allow to idle (using gasoline in carburetor bowl). Observe pressure gauge. Pressure should be about 4-7 psi (.28-.49 kg/cm 2 ) for 4-cylinder and V6 engines, and about 6-9 psi (.42-.63 kg/cm 2 ) for V8 engines.
3. If pressure is too low, check fuel lines or gasoline tank filter for restrictions or leaks. If lines and filter are clear, pump is defective. If pressure is incorrect or varies greatly with the engine speed, replace the fuel pump.

1. Reconnect fuel line to carburetor inlet and check for leaks. Disconnect hose at inlet side of fuel pump. Raise end of hose so fuel will not run out. Connect vacuum gauge to pump inlet with short length of hose.
2. Start engine and allow to idle. Check vacuum level. Gauge should read at least 5-7.7 in. Hg. If not, replace pump.

SPECIFICATIONS

FUEL PUMP SPECIFICATIONS (TYPICAL)