Section 10-00: Fuel System—Service 1992 Town Car/Crown Victoria/Grand Marquis Workshop Manual SPECIFICATIONS Fuel System—ServiceRefer to the Engine/Emissions Facts Book and Calibration number.
FUEL PRESSURE SPECIFICATIONS Description Specification Engine Running 30-45 psi 210-310 kPa Key On Engine Off 35-40 psi
240-280 kPa
Section 10-00: Fuel System—Service 1992 Town Car/Crown Victoria/Grand Marquis Workshop Manual DIAGNOSIS Fuel System—Service
Wiring Diagram
Almost any electric fuel pump malfunctions that can occur will result in a loss or reduction of fuel flow and/or pressure. Loss of pressure and/or flow will be defected by a reduction of engine performance. The diagnostic procedures will concentrate on determining if the electric duel pump is operating properly. Other diagnostic procedures will cover the analysis of other malfunctions that can cause losses or reductions of engine performance.
Use the diagnosis charts to determine if the electric fuel pump is operating properly. PINPOINT TEST: A FUEL PUMP DIAGNOSIS A1 INITIAL SYSTEM INSPECTIONCheck fuel system for adequate fuel supply.Visually inspect the fuel delivery system including fuel tank lines, filter, injectors, pressure regulator, battery, electrical lines and connectors for leakage, looseness, cracks, pinching, kinking, corrosion, grounding, abrasion, or other damage caused by accident, collision, assembly or usage.Verify that the battery is fully charged.Check fuse integrity.Is the system free of any evidence of leakage damage, or any evident cause for concern?Yes
GO to A2.
NoSERVICE or REPLACE. GO to A2.
A2 STATIC FUEL PRESSURE CHECKInstall the fuel pressure tester.Check for a connection at the FP lead ground FP lead if present. If no connection exists, check for separate connector located in the area. The test connector is a two pin connector. Use the "spout" or similar connector to jumper this connection to run fuel pump.Turn the ignition key to the RUN position to operate the fuel pump.Verify that the observed fuel pressure is within specified limits for the engine being tested (refer to chart).
Is the fuel pressure within specifications?
YesGO to A3.
NoIf pressure is high, GO to A5.
If pressure is low, GO to A6.
A3 STATIC LEAKDOWN TESTRun fuel pump for 10 seconds and note pressure (ground FP lead of self test connector and turn ignition switch to the RUN position).Turn off pump and monitor pressure for 60 seconds. (Remove ground or turn ignition switch to the OFF position).Does fuel line pressure remain within 34 kPa (5 psi) of shut off pressure for 60 seconds?
YesGO to A4.
NoGO to A10.
A4 VEHICLE LOAD TESTRemove and block vacuum hose to pressure regulator.Run vehicle at idle and then increase engine speed to 2000 rpm or more in short bursts.
Does fuel system pressure remain within chart limits?
NOTE: Running vehicle under load with vacuum hose removed from fuel pressure regulator (road test) may give better results.
YesFuel system is OK. DISCONNECT all test connections. CONNECT vacuum hose to pressure regulator.
NoGO to A12.
A5 FUEL PRESSURE REGULATOR CHECK Disconnect return line at fuel pressure regulator. Connect outlet of regulator to appropriate receptacle to catch return fuel.Turn on fuel pump (ground FP lead and turn ignition to the RUN position) and monitor pressure.Is fuel pressure within chart limits?
YesCHECK and SERVICE return fuel line for restrictions. RECHECK pressure as in A2. GO to A3.
NoREPLACE fuel regulator. RECHECK pressure as in A2. GO to A3.
A6 CHECK FUEL PUMPTurn on fuel pump (ground FP lead and turn ignition to the RUN position).Raise vehicle on hoist and use stethoscope to listen to fuel tank to monitor fuel pump sound.Is fuel pump running?
YesGO to A9.
NoGO to A7.
A7 INERTIA SWITCH AND GROUND CHECKCheck inerita switch to see if it is open.Check fuel pump ground connection in vehicle.Are inertia switch and ground connections OK?
YesGO to A8.
NoRESET or REPLACE switch or SERVICE ground connection as required. RECHECK pressure as in A2. GO to A3.
A8 VOLTAGE CHECKCheck for continuity through fuel pump to ground by connecting to pump power wire lead as close to pump as possible.Check voltage as close to fuel pump as possible (Turn on pump as indicated in A6).Is voltage within 0.5 volts of battery voltage and is there continuity through pump?
YesREPLACE fuel pump and RECHECK pressure as in A2. if pressure is OK, GO to A3.
If pressure is not OK, RECHECK fuel pump connector for oversize connectors or other sources of open electrical circuit. SERVICE as required. GO toA3.
NoGO to A12.
A9 PRESSURE REGULATOR CHECKReplace fuel filter (if not replaced previously) and recheck pressure as in A2. If pressure is not OK, continue. If pressure is OK, go to A3.Open return line at pressure regulator. Attach return fitting from regulator to suitable container to catch gasoline.Turn on fuel pump as in A2.Is fuel being returned from regulator with low pressure in system?
YesREPLACE regulator. RECHECK pressure as in A2 and GO to A3 if OK.
If not OK, REPEAT Step A2 until trouble found. If trouble not located, REPLACE pump and REPEAT A2 .
NoRECHECK system for pressure restrictions and if none found, REPLACE pump. RECHECK pressure as in A2 and continue to A3.
A10 PRESSURE REGULATOR LEAK TESTOpen return line at pressure regulator and attach suitable container to catch return fuel. Line should be clear to observe fuel flow.Run fuel pump as in A2.Turn off fuel pump by removing ground from self test connector or turning ignition to OFF.Observe fuel return flow from regulator and system pressure when pump is off.Remove vacuum hose from fuel pressure regulator and check for presence of fuel in regulator fitting (diaphragm leak).Is there return flow when pump is turned off and system pressure is dropping or fuel in regulator fitting?
YesREPLACE regulator and RECHECK pressure and leakage as in A2 and A3. If OK, GO to A4. If not OK, REPEAT Step A2 and follow procedure.
NoGO to A11.
A11 PUMP CHECK VALVE TESTOpen pressure line from fuel pump and attach pressure gauge to line and block line to allow pressure build up.Operate pump momentarily as in A2 and bring pressure to about system pressure.Observe fuel pressure for one minute.Does pressure remain within 34 kPa (5 psi) of starting pressure over one minute period?
YesCHECK injectors for leakage or regulator for internal leakage. Fuel pump check valve is OK. When serviced GO to A4.
NoCHECK lines and fittings from pump to rail for leakage, if none found, REPLACE pump assembly. RECHECK pressure as in A2 and when OK, GO to A4.
A12 FUEL SYSTEM RESTRICTION OR USAGE TESTReplace fuel line filter (if not previously replaced during this procedure) and repeat test A5.Does system pressure remain within chart limits?
YesSystem is OK, DISCONNECT all test connections and RECONNECT all loosened or removed parts and lines.
NoCHECK pressure lines for kinks or restrictions. CHECK at fuel pump for low voltage. GO to A13. CHECK for wrong size injectors (too large). If no concern found, REPLACE pump and REPEAT A4.
If concern found, SERVICE and REPEAT A4.
A13 CHECK VOLTAGE AT FUEL PUMP RELAYKey OFF.Battery fully chargedGround fuel pump lead of the VIP Self-Test connector as shown.Key ON, engine OFF.DVOM on 20 volt scale.Measure the voltage at the fuel pump relay contact "A" as shown.
Is voltage greater than 10.5 volts?
YesSERVICE wire from fuel pump relay to inertia switch. GO to A2.
NoGO to A14.
A14 CHECK CHECK POWER SUPPLY TO FP RELAYKey OFF.Remove fuel pump relay.Key ON, engine OFF.DVOM on 20 volt scale.Check relay socket for voltage at Pins C1, C2, and A or NO.
Does relay socket have voltage at 2 pins as indicated?
YesGO to A17.
Neither contact C1 nor C2GO to A15.
Neither contact A nor NOCHECK fuel pump fuse or fuse link and wiring between relay and contact. SERVICE as needed and INSTALL relay. GO to A2.
A15 CHECK EEC RELAY AND WIRINGKey OFF.Remove EEC Relay.Key ON, engine OFF.DVOM on 20 volts.Check relay socket for voltage at Pins C1, or C2 and A or NO.Note which pins have voltage present (there should only be voltage on one pin of each pair, if voltage present on both pins of one pair, look for shorted wiring).
Are voltages greater than 10.5 volts on relay socket?
YesGO to A16.
Neither contact C1 nor C2CHECK and SERVICE wiring between ignition switch and relay coil then INSTALL relay. GO to A2.
Neither contact A nor NOSERVICE wiring or REPLACE fuse or fuse link between EEC relay and contact then INSTALL relay. GO to A2.
A16 CHECK EEC RELAY GROUNDKey OFF.EEC relay removed.DVOM on low OHMS scale.Check EEC relay coil pin which did not have voltage in StepA18(either C1 or C2) for ground.Is ground on coil pin of EEC relay less than 1 ohm?
YesGO to A17.
No.SERVICE ground wire at EEC relay, REINSERT EEC and fuel pump relays and GO to A2.
A17 CHECK FUEL PUMP OR EEC RELAYRemove relay from vehicle.Connect a +12 volt supply to terminal C1 as shown.Ground terminal C2 as shown.DVOM on 200 ohm scale.Measure the resistance between terminals A and NO as shown.
Is resistance lower than 1 ohm with power on and greater than 10K ohms with power off?
YesGO to A18.
NoREPLACE and REINSERT fuel pump and/or EEC relay as required. GO to A2.
A18 CHECK VOLTAGE AT PIN 22 (PROCESSOR)Key OFF.Battery fully charged.Remove EEC-IV processor.Install Rotunda breakout Box, T83L-50-EEC-IV, or Rotunda EEC-IV Monitor 007-00018 or equivalent.Key ON, engine OFF.DVOM on 20 volt scale.Measure the voltage on Pin 22 of the breakout box,orWith EEC-IV Monitor, install the appropriate overlay according to engine size and year. Place selector switch "A" on Pin 22, "FP", turn EEC-IV Monitor power on and read voltage on Pin 22 from LCD readout.Is voltage greater than 10.5 volts?
YesCHECK processor for malfunction. After condition is corrected, GO to A2.
No.SERVICE wire between EEC-IV and FP relay/IRCM. CHECK at VIP connector for lead presence. GO to A2 when condition has been corrected.
