Service Procedure

Attempt to duplicate stall while the New Generation Star (NGS) Tester is connected to the vehicle. Monitor Parameter Identification Display (PID) for evaporative emission purge duty cycle (EVAPPDC), both front Heated Exhaust Gas Oxygen (HEGO) sensors (O2S11 and 02S21), and long and short fuel trim (SHRTPT1, LONGFT1). Normal operating range for the long and short fuel trim is +/- 10%. If, during the stall, the engine goes rich, then lean (the SHRTFT1 is greater than +/- 15% for a length of time), and the Vapor Management Valve (VMV) is open (from 30% to 100%) perform the following:

1. Remove the evaporative emission canister from the vehicle.

a. Inspect the EVAP canister for water or liquid fuel contamination.

b. Check for restrictions in all the hoses attached to the EVAP canister (canister vent tube, short tube that connects both canisters, and vacuum tube from canister to VMV).

c. Verify plastic screens and green foam that prevent the carbon particles from escaping the canister are in their correct position at all four (4) hole locations on the top of the canister.

2. If water is found in the canister, verify water entry source (loose hose) is corrected. Replace the EVAP Canister (F5AZ-9D653-B). Verify carbon has not migrated from canister into VMV vacuum line. If carbon is found in this line, it may have been ingested by the VMV. Replace both the Vacuum Line (F1AZ-9324-A) and VMV (F5AZ-9C91 5-A).

3. If liquid fuel is found in the carbon canister:

a. Verify the fuel filler pipe signal tube (small tube brazed to the filler pipe) is not blocked.

^ 1) Check by removing the gas cap, disconnect the plastic fitting at the base of signal tube and blow compressed air into the signal tube. Air should flow through the tube and out the gas cap opening.

^ 2) If the tube is blocked, replace filler pipe.

^ 3) If not blocked, reattach plastic fitting to signal tube.

NOTE
IF REPLACING THE FILLER PIPE WITH THE PARTS LISTED IN THE FOLLOWING STEP 3b, THE VAPOR CONTROL VALVE (VCV) (F6AZ-9C047-BA) MUST ALSO BE CHANGED.

b. Inspect the convoluted tube that goes from the signal tube to the VCV on top of the gas tank for restrictions. If the line is disconnected from the clip on the fuel tank flange, it may be crushed between the fuel tank and floor sheet metal.

^ 1) Verify plastic signal tube is functioning properly using Rotunda Evaporative Emissions Tester.

^ 2) Pressurize the EVAP system at the fuel filler cap to recommended pressure.

^ 3) Disconnect the plastic hose that attaches to the stainless steel tube that goes to the EVAP canister.

^ 4) Feel for air flow from the connector. If no air flow, replace the VCV on top of the fuel tank and reattach all connections.

NOTE
WHEN REPLACING THE VCV, THE FUEL FILLER PIPE MUST BE REPLACED WITH A FILLER PIPE THAT DOES NOT HAVE THE SMALL SIGNAL TUBE BRAZED TO THE FILLER PIPE (F6AZ-9034-DA) (NEW VCV DOES NOT REQUIRE A SIGNAL LINE).

NOTE
REPLACE THE FUEL TANK STRAP STUDS WITH NEW STUDS (N808979-S191) PRIOR TO REINSTALLING THE FUEL TANK. REFER TO THE 1996 CROWN VICTORIA/GRAND MARQUIS SERVICE MANUAL, SECTION 10-01A, FOR FUEL TANK INSTALLATION PROCEDURE.

c. Inspect vacuum hose from canister to VMV for carbon. If carbon has migrated into the hose, replace the hose and the VMV. Blow compressed air through the stainless steel tube from the canister to the VCV to clear any liquid fuel in the line.

d. Check the fuel filter (located on left frame rail) for presence of carbon. If found, replace the Fuel Filter (E7DZ-9155-A), drop gas tank and inspect the fuel pump sending unit filter and gas tank for carbon contamination. Flush the fuel tank and service the fuel pump as required.