Note

You are in the Fuel Delivery Diagnosis section, although the problem may be elsewhere.

Remember

To prevent the replacement of good components, the following areas may be at fault:

• Battery and charging system low (fuse integrity).
• Contamination within the Idle Air Control (IAC) device.
• Contamination of fuel.
• Octane rating.
• Plugged or restricted fuel filter.
• Engine not reaching operating temperature.
• Cooling system (low/leaking).
• PCV system (incorrect/clogged).
• Transmission, Clutch integrity.
• Brakes (not releasing).
• Ignition system.
• Exhaust system, EGR.
• Vacuum leaks (air intake manifold, vacuum hoses, vacuum reservoirs, power brake booster, as applicable).

Verify

• Transmission in PARK or NEUTRAL.
• Parking brake applied (automatic brake release disconnected where applicable).
• Wheels blocked.
• Transmission fluid integrity.
• Transmission shift timing.
• Adequate fuel supply in the tank.
• Fuel system integrity (leaks, restricted or damage).
• Fuel system electrical integrity (Inertia Fuel Shutoff (IFS) switch).
• Generator belt tension.
• Heater and accessories off.
• Throttle lever is resting on the throttle plate stop screw.
• EEC-IV diagnostics have been performed and the vehicle malfunction indicated by Diagnostic Trouble Codes (DTCs) has been resolved.

Note: For additional information, refer to Fuel/Engine Group in the Car or Truck Service Manual.

 CAUTION: Use care to prevent combustion from fuel spillage. No smoking, open flames or any kind of arcing.

FIRE

• REPORT ALL FIRES to the appropriate authorities.
• FLAMES from methanol or methanol-gasoline blends MAY BE INVISIBLE.
• Know the location of PORTABLE FIRE EXTINGUISHERS, FIRE BLANKETS, FIRE ALARMS and EYE WASH/SHOWER FACILITIES. Learn how to use them.
• Use a B or AFFF (light water) type FIRE EXTINGUISHER to fight flammable liquid fires.

FIRST AID

• IF SWALLOWED:
• If GASOLINE has been swallowed, DO NOT induce vomiting. SEEK MEDICAL ATTENTION IMMEDIATELY!
• If METHANOL OR A METHANOL/GASOLINE BLEND has been swallowed, induce vomiting under the direction of a physician or Poison Control Center. SEEK MEDICAL ATTENTION IMMEDIATELY.
• When overcome by vapors, MOVE VICTIM TO FRESH AIR if safe. If not breathing, give artificial respiration or Cardiopulmonary Resuscitation (CPR) as appropriate. SEEK MEDICAL ATTENTION IMMEDIATELY.
• If SPLASHED IN EYES, FLUSH with large amounts of water for 15 minutes. Remove contact lenses, if worn. Seek medical attention.
• If SPLASHED ON SKIN, REMOVE CONTAMINATED CLOTHING. WASH SKIN thoroughly with soap and water.

HEALTH

• ALL FUELS may be HARMFUL OR FATAL IF SWALLOWED.
• BE AWARE, IF SWALLOWED, onset of serious health effects may be delayed 12 to 24 hours.
• FUELS AND PRODUCTS containing methanol (e.g. windshield washer fluid) may cause blindness if swallowed.
• ALL FUEL VAPORS may be HARMFUL BY INHALATION.
• ALL FUELS may be HARMFUL BY SKIN ABSORPTION.
• ALL FUELS are IRRITATING to the EYES and RESPIRATORY SYSTEM.
• FUELS made with GASOLINE may contain benzene which is a cancer-causing agent.

HANDLING

• Use FLAMMABLE LIQUID HANDLING PRECAUTIONS.
• Wear CHEMICAL GOGGLES and NITRILE GLOVES (additional protective clothing and equipment may be necessary in some instances).
• Keep flammable liquids in APPROVED, LABELED, CLOSED CONTAINERS.
• Use in WELL-VENTILATED AREAS and CONTROL VAPORS. Be aware that vapors ARE NOT VISIBLE, are heavier than air, can travel along the floor, and will settle in lower areas.
• When transferring flammable liquids, BOND the RECEIVING CONTAINER to the SOURCE and GROUND the SOURCE to the EARTH.
• DO NOT SMOKE or use HEAT/SPARK PRODUCING EQUIPMENT near vapors.
• DO NOT eat, smoke or drink where these products are handled, processed or stored.
• NEVER SIPHON BY MOUTH.
• WASH HANDS thoroughly after HANDLING any FUEL.

SPILLS

• Notify the proper authorities in the EVENT of any spill you have NOT been trained to clean up.
• STOP, CONTAIN, AND CLEAN UP small spills with an absorbent material.

 WARNING: FUEL IN THE FUEL SYSTEM REMAINS UNDER HIGH PRESSURE EVEN WHEN THE ENGINE IS NOT RUNNING. TO AVOID INJURY OR FIRE, RELEASE THE FUEL PRESSURE FROM THE FUEL SYSTEM BEFORE DISCONNECTING ANY FUEL LINE. TO RELEASE THE PRESSURE FROM THE SYSTEM PERFORM THE FOLLOWING:

• CONNECT THE ROTUNDA FUEL PRESSURE TESTING KIT 014-00447 OR EQUIVALENT AT THE SCHRADER VALVE LOCATED ON THE FUEL RAIL WITH THE TESTING KIT VALVE CLOSED.
• GRADUALLY OPEN THE TESTING KIT VALVE TO RELIEVE FUEL PRESSURE IN THE VEHICLE FUEL SYSTEM AND DRAIN THE FUEL INTO A SUITABLE CONTAINER OR RETURN IT TO THE FUEL TANK.
• TO AVOID UNNECESSARY FUEL SPILLAGE AND FIRE HAZARD AT ANY TIME FUEL LINES ARE DISCONNECTED, THE IGNITION SWITCH SHOULD BE IN THE OFF POSITION UNLESS FUEL PUMP OPERATION IS REQUIRED FOR TEST PURPOSES.

The electric fuel delivery systems differ in design and arrangement depending upon the vehicle and model year. To clarify understanding and to simplify diagnostic instruction, they are classified as either Type 1 (Single Tank) or Type 2 (Dual Tank):

• Type 1: Single Fuel Delivery Assembly or In-Tank Fuel Pump Assembly
• Type 2: Dual Fuel Delivery Assembly (one assembly per tank)

In order to continuously supply the fuel injectors with clean fuel at a controlled pressure, all systems require a fuel pump with a discharge check valve, a reservoir surrounding the pump inlet, a fine mesh fuel filter, a pressure regulator, a fuel supply and return system of tubes and hoses, a fuel tank, and a fuel supply manifold or fuel rail connected to the fuel injectors. The Powertrain Control Module (PCM) controls power input to the fuel delivery system and provides correct timing for the fuel injectors.

The in-tank fuel pump assembly (Figure 1) has a discharge check valve (to maintain system pressure during shutdowns and to minimize starting problems), an inlet screen for protection and fuel return provision. The pump on the 3.0L Taurus FF has an additional fuel line tap used for draining the tank.

The Fuel Delivery Assembly (Figure 2) consists of the fuel pump inside a reservoir that is attached to the pump and sender assembly. In a two tank system there is one assembly per tank. The sender assembly handles the switching of the fuel through internal valves. To service the assembly, replace it.

Fuel reservoirs are used to prevent fuel flow interruptions during extreme vehicle maneuvers with low tank fill levels. The reservoir is located in-tank and is either moulded or welded into the tank or is part of the Fuel Delivery Assembly.

The system contains four filtering or screening devices:

1. The fuel intake sock is a screen located on the intake side of the fuel pump and is part of the fuel pump assembly.

2. The filter screen on the fuel rail port of the injector is part of the fuel injector assembly and cannot be serviced separately.

3. The filter screen on the fuel inlet side of the pressure regulator is part of the fuel pressure regulator assembly and cannot be serviced separately.

4. The fuel filter assembly is located between the fuel pump and the Schrader valve or injectors. This filter should be serviced periodically by replacing it.

The Shuttle Selector Valve opens the return line to the tank when the fuel pressure on the shuttle diaphragm exceeds the opposing spring force. The return flow is directed to the appropriate tank on vehicles equipped with dual tanks.

The Supply Check Valve, which is normally closed, opens when the outlet pressure from the energized pump exceeds the opposing check valve spring force. When the pump is de-energized (i.e., engine is shut off), the supply check valve closes to maintain pump prime and fuel supply line pressure.

A portion of the high pressure flow from the pump is diverted to operate the Venturi Jet Pump. The Venturi Pump draws fuel from the tank into the assembly. This process ensures an adequate fuel supply to the pump during extreme vehicle maneuvers and steep vehicle attitudes with low-tank fuel fill levels.

The inlet of the Venturi Pump has a nylon filter on it to prevent dirt and other particulate matter from entering the system. Water in the fuel tank can pass through the filter in small quantities.

The Fuel Pressure Regulator (Figure 3) is attached to the fuel supply manifold assembly downstream of the fuel injectors. It regulates the fuel pressure supplied to the injectors. The regulator is a diaphragm-operated relief valve. One side of the diaphragm senses fuel pressure and the other side is connected to the intake manifold vacuum. Nominal fuel pressure is established by a spring preload applied to the diaphragm. Balancing one side of the diaphragm with manifold vacuum maintains a constant fuel pressure drop across the injectors. Fuel in excess of that used by the engine is bypassed through the regulator and returns to the fuel tank.

A pressure test point with a Schrader fitting is in the engine fuel rail to relieve pressure in the fuel system and to measure the injector supply pressure for service and diagnostic work. Refer to Caution and Warning.

The IFS switch (Figure 4) is used in conjunction with an electric fuel pump. The purpose of the IFS switch is to shut off the fuel pump in the event of an accident. It consists of a steel ball held in place by a magnet. When a sharp impact occurs, the ball breaks loose from the magnet, rolls up a conical ramp and strikes a target plate which opens the electrical contacts of the switch and shuts off the electric fuel pump. Once the switch is open, then it must be manually reset before restarting the vehicle. Some vehicles have a fuel reset light. For the location of the IFS switch, refer to the Owner Guide.

1. Turn ignition to OFF.

2. Check for leaking fuel in the engine compartment, fuel lines and tank(s).

3. If no fuel leak is apparent, reset the IFS switch by pushing the reset button on the top of the switch (refer to Owner Guide). Note in the closed position the button can be depressed on additional 1/16 inch against a spring.

4. Turn ignition switch to START for a few seconds, then to OFF.

5. Again, check for leaking fuel.

 WARNING: IF YOU SEE OR SMELL GASOLINE AT ANY TIME OTHER THAN REFUELING, DO NOT RESET THE IFS SWITCH.

The Fuel Injector (Figure 5) is a solenoid operated valve that meters fuel flow to the engine. The injector is opened and closed a constant number of times per crank revolution. The amount of fuel is controlled by the length of time it is held open.

The injector is normally closed. It is operated by 12V VPWR from the EEC-IV Power Relay and the ground signal is controlled by the Powertrain Control Module (PCM).

Note: Do not apply battery voltage directly to the injector electrical connector terminals. The solenoid may be damaged internally in a matter of seconds.

Passenger Car, Aerostar, Ranger, Explorer.

3.0L FF Taurus.

E-Series, F-Series/Bronco.

F-Series.

Escort/Tracer, Crown Victoria/Grand Marquis, Thunderbird/Cougar, Town Car, 5.0L Mustang, Aerostar, Ranger, Explorer, E-Series and Bronco.

1. The electrical circuit of the Inertia Fuel Shutoff (IFS) switch may vary per engine/vehicle application.
2. Inertia Fuel Shutoff (IFS) switch with fuel reset light (F-Series and Bronco).
3. Inertia Fuel Shutoff (IFS) switch with fuel reset light (Town Car).

3.0L Taurus FF.

Mark VIII.

Tempo/Topaz, 3.0L Taurus SHO, Taurus/Sable and Continental.

F-Series.

When the ignition is switched to the ON position, it turns the EEC Power Relay on. The EEC Power Relay provides power to the EEC-IV processor and the control side of the fuel pump relay. Power for the fuel pump is supplied through a fuse link or high current fuse attached to the starter solenoid (battery side). From the fuse link or high current fuse, current flow is through the fuel pump relay and Inertia Fuel Shutoff (IFS) switch to the fuel pump. The IFS switch is a safety device used to shut off the fuel pump in the event of a collision. If the IFS switch is "tripped," it must be reset by depressing the white or red button on the top of the switch. The fuel pump relay is controlled by the Powertrain Control Module (PCM).

When the ignition switch is turned to the ON position, the fuel pump will operate. If the ignition switch is not turned to the START position, the PCM will shut the fuel pump off after approximately one second. The PCM will operate the fuel pump when the ignition is in the START position to provide fuel while cranking.

After the engine starts, the PCM will continue to operate the fuel pump unless the engine stops, engine speed drops below 120 rpm, or the IFS switch is "tripped."

The Taurus Flex Fuel and Mark VIII have a DUAL FUEL PUMP VOLTAGE system (Figures 11 and 12) to aid in fuel system noise concerns. The fuel pump operates in the high voltage mode (12-14 volts) during crank (for 5 to 60 seconds depending upon engine temperature), after start-up, at engine speeds in excess of 3300 rpm, and during periods of Wide Open Throttle when maximum fuel delivery may be required. The normal operating mode calls for low voltage (7-10 volts) to the fuel pump. This minimizes operating noise. Fuel pump operation is controlled by the PCM. The fuel pump operates in the same manner as all other systems except for the two speed feature. For diagnosing fuel pump noise in the Taurus Flex Fuel, GO to FDS15.

Note: Maximum fuel pressure is obtainable at WOT or the vacuum hose removed from the fuel pressure regulator.

If fuel lines/systems have been drained or evacuated, it may take up to 15 seconds to obtain the pressure specified.

System Diagnosis

Note: Grounding the FP lead at the DLC will allow the pump to run continuously with the ignition switch on.