Service Procedure
WARNING:Before performing any of the Service Procedures below, be certain there are no ignition sources (i.e., open flames, sparks, etc.) in or around the vehicle/work area. Make sure the appropriate rated fire extinguisher is available for immediate use.
1. Confirm that DTC P1491 is stored in "Self-Diagnosis Results".
2. Release the fuel pressure from the fuel system using CONSULT-II (or other suitable method) following the ESM procedure.
3. Use a suitable device to remove the fuel from the fuel tank.
4. Remove the fuel tank sending unit. The procedure will be different, depending on which model you are working on, Frontier or Xterra.
For Xterra; the fuel tank does not need to be removed.
a. Remove the right rear passenger seat bottom cushion and fuel tank sending unit access cover.
b. Refer to the appropriate section of the ESM for fuel tank sending unit removal.
c. Go to step 5.
For Frontier; the fuel tank must be removed to access the fuel tank sending unit.
a. Mark the pipes and hoses (attached to the fuel filler neck) before disassembly.
b. Use duct tape and an indelible marker (see Figure 1).
c. The hoses and pipes must be marked for correct re-assembly.
d. If the hoses are later re-connected incorrectly, refueling difficulties may occur.
NOTE:
Refer to the vehicle specific Service Manual, Section FE (Fuel And Exhaust)/Fuel System/Removal and Installation/Fuel Tank for detailed instruction on fuel tank removal and installation.
WARNING:
Follow all warnings and cautions provided in the Service Manual.
5. In preparation for working inside the fuel tank, place a split piece of rubber vacuum hose or other suitable covering onto the edge of the fuel tank sending unit opening to prevent injury.
WARNING:
The fuel tank sending unit opening edge is sharp.
6. Determine the Shutter Valve need for your vehicle.
a. All 2002 Frontier and Xterra vehicles built after January 1, 2002 have the new style shutter valve installed at the factory. Do not replace the shutter valve. Proceed to step 9.
b. All 2002 Frontier and Xterra vehicles built before January 1, 2002 have the old style shutter valve installed at the factory. Replace the shutter valve with the one listed in the Parts Information. See steps 7 and 8 for shutter valve replacement.
NOTE:
If you do not know the exact build date of the vehicle you are working on: it can be found in service comm.
7. If needed, remove the fuel shutter valve from inside the fuel tank (see Figure 2).
^ For tanks with a black rubber hose connecting the white plastic fuel shutter valve inside the tank (type 1, see Figure 3);
a. Loosen the screw-type hose clamp on the rubber hose next to the inside wall of the fuel tank.
b. Remove the complete hose and shutter valve.
c. Discard the removed parts.
^ For tanks with only a white plastic shutter valve (type 2, see Figure 3);
a. Remove the shutter valve with a twisting motion while pulling it straight off.
b. Discard the removed parts.
8. Install the replacement shutter valve (see Figure 4).
a. Lube the 0-ring inside the replacement shutter valve with Texaco Canopus 13 Mineral Oil (see Figure 3).
b. Push the new shutter valve onto the tube where the old shutter valve was removed.
c. Ensure that the new shutter valve is pushed all the way onto the tube and it "snaps" into position.
NOTE:
The opening (the Shutter "door") should be pointing straight down toward the fuel tank bottom when installation is complete (see illustration on right above).
9. Install the Fuel Cut Valve Kit inside the fuel tank (see Parts Information and Figure 5).
a. Route the rubber hose around the metal support bracket.
b. Snap the three mounting clips onto the existing metal tube.
c. Push the rubber hose end onto the recirculation line (metal tube that is not attached to anything else).
10. Reinstall the fuel tank sending unit using the new 0-ring supplied with the Fuel Cut Valve Kit.
11. Remove trapped fuel in EVAP system signal line.
For Frontier (with tank removed from vehicle. see Figure 6).
a. Attach one end of a clear rubber tube to the signal line on the outside of the fuel tank.
b. Attach the other end of the clear rubber tube to a hand vacuum pump.
NOTE:
Put a U-bend in the rubber tube between the fuel tank and the vacuum pump to "hold" any fuel removed from the signal line. If fuel gets into your hand vacuum pump it may become damaged.
c. Apply vacuum to remove any fuel that may be trapped in the signal line.
For Xterra (with fuel tank installed in the vehicle)
a. Remove fuel line protective cover in the right rear wheel well (see Figure 7).
b. Remove rubber signal hose from the lower metal signal line tube (see Figure 8).
c. Attach one end of a clear rubber tube to the signal line hose (see Figure 8).
d. Attach the other end of the clear rubber tube to a hand vacuum pump.
NOTE:
Put a U-bend in the rubber tube between the fuel tank and the vacuum pump to "hold" any fuel removed from the signal line. If fuel gets into your hand vacuum pump it may be damaged (see Figure 8).
e. Apply vacuum to remove any fuel that may be trapped in the signal line.
12. For FRONTIER; reinstall the fuel tank and reconnect all hoses and connectors removed during tank removal, then go to step 26.
NOTE:
For instructions on replacing the fuel tank, refer to the vehicle-specific Service Manual, Section FE (Fuel and Exhaust)/Fuel System/Removal And Installation/Fuel Tank. Follow all warnings and cautions provided in the Service Manual.
For XTERRA ONLY; Perform steps 13 through 25 to install the "ground jumper Wire" listed in the Parts Information.
13. Remove the following items:
^ Passenger side kick panel
^ Front passenger seat (Be careful not to break the seat belt electrical harness connector.)
^ Right front seat belt floor anchor bolts (located at the base of the "B" pillar).
^ Right side front and rear "kicking plates" (door sill covers)
^ The right rear seat cushion. (Seat cushion should have already been removed when fuel sending unit was accessed.)
^ Pull the carpet and insulation away from the right side of the vehicle to reach the electrical harness (body No. 2 harness).
14. Remove bolt for ground point M68, and add one end of the jumper wire to this ground point (see Figure 9).
Reinstall the bolt and confirm it is properly secured.
15. Remove the body harness cover/protector along the right front door opening (see Figure 10).
16. Route the jumper wire along the body harness and tie-wrap it to the body harness (see Figure 10).
NOTE:
Use local supplier for tie-wraps.
17. Remove the screws and lift the body harness with cover near the B-pillar (see Figure 11).
18. Route the jumper wire along the harness inside the harness cover and under the existing electrical tape (see Figure 11).
19. Still working your way back: route the jumper wire along the body harness and inside/through the protective cover near the right rear door opening (see Figure 12).
20. Remove the bolt at ground point B106 and add the end of the jumper wire to this ground point (see Figure 13).
Reinstall the bolt and confirm it is properly secure.
21. Use tie-wraps to secure the excess jumper wire to the existing body harness (see Figure 13)
22. Go back along the jumper wire entire length. Double check and make sure you've used enough tie-wraps to secure the jumper wire to the body harness between ground points M68 and B106 (see Figures 9 through 13).
23. Cut off excess length on each tie-wrap.
24. Place the body harness back into its position and reinstall covers and mounting screws.
25. Reinstall the following items:
^ Fuel level sending unit access cover
^ Put floor insulation and carpet back in place
^ Right rear passenger seat bottom cushion
^ Right side front and rear "kicking plates" (door sill covers)
^ Right front kick panel
^ Right front seat belt floor anchor bolts (located at the base of the B pillar). Torque these anchor bolts to 43.1 68.6 N-m, (4.4-7.0 kg-m, 32-50 ft-lb.).
^ Front passenger seat (make sure to connect the seat belt harness connector). Torque the bolts to 43-55 N-m, (4.4-5.6 Kg-m, 32-41 ft-lb.).
26. Refuel the vehicle. Check for proper operation and that there are no fuel leaks.
27. Erase the DTC using CONSULT-II. Return the vehicle to the customer.