Fuel System—Pressurized

Fuel Lines, Steel

EFI systems are equipped with an electric fuel pump (9350) that provides fuel to the engine at higher pressure than conventional fuel systems. For electric fuel pump diagnosis and testing, refer to Section 10-00. A fuel return system is also provided. All fuel hose/tube connections are made with push connect fittings, and all hoses are serviced as assemblies. The metal tubes attached to the vehicle underbody may be serviced and repaired. The metal underbody tubes must be cut and formed out of rolls of fuel system service tubing available at the dealerships.

A damaged section of tubing can be cut out of the existing line and replaced by a comparable service tubing section, spliced into the line by means of threaded fasteners and connectors.

All replacement hoses must be serviced as assemblies. Refer to Push Connect Fitting Installation for connecting procedure. Bulk fuel hose must not be used to service tubing in high pressure fuel systems.

 WARNING: FUEL SUPPLY LINES ON VEHICLES EQUIPPED WITH FUEL INJECTED ENGINES WILL REMAIN PRESSURIZED FOR LONG PERIODS OF TIME AFTER ENGINE SHUTDOWN. THE PRESSURE MUST BE RELIEVED BEFORE SERVICING THE FUEL SYSTEM. REFER TO FUEL SYSTEM PRESSURE RELIEF.

Removal

1. Drain the fuel from the fuel tank (9002) as outlined.

2. Disconnect the line(s) at the fuel tank and at the engine. Remove the lines from the holding clips along the underbody. Remove all damaged hoses and tube sections.

Installation

NOTE: After disassembly of the flareless fitting joint, such as at the fuel hose to fuel line connection, the flareless fitting can be reassembled. To reassemble, reconnect the threaded fitting and seat the ferrule to be finger-tight. When the ferrule is seated, draw the nut up approximately one-sixth to one-third of a turn with a wrench to complete the tightening operation.

1. Cut a new section of tubing to approximately the same length as the section to be replaced, allowing for the threaded connectors/fasteners.

2. Bend the tube section to conform to the contour of the original tube.

3. Square the ends of the cut tubing with a file. Remove burrs. Blow out any particles with compressed air.

4. Position the lines in the underbody clips. Do not tighten at this time.

5. Assemble the fitting by sliding the nut over the tubing with threaded (open) end out.

6. Slide the ferrule on the tubing with the cutting edge out, the large head end should be inside of the nut.

7. Lubricate the ferrule and the threads on the fasteners with oil.

8. Bottom the tube in the fitting, and tighten the nut until the ferrule just grips the tube. When the tube can no longer be turned by hand, the ferrule has started to grip the tube.

9. After the ferrule grips the tube, tighten the nut one full turn.

10. Tighten the fuel line to the underbody clips to secure the fuel lines.

11. Fill the fuel tank and check for leaks.

Fuel and Vapor Return Tubes

Vehicles equipped with nylon fuel tubes and push connect fittings have three types of service that can be performed to the fuel lines: replacing nylon tubing (splicing nylon to nylon), replacing push connector fittings and replacing damaged push connect tube end. These methods follow:

Splicing Nylon to Nylon

1. Relieve fuel system pressure as outlined. Read cautionary note prior to relieving pressurized fuel system. If necessary, drain fuel from fuel tank as outlined.

2. Cut out damaged section of tubing and retain as a guide.

3. Cut a section of service tubing (type 11 or 12 nylon available in 1/4 and 5/16 inch sizes) to the same length as the damaged section of tubing.

   NOTE: To make hand insertion of the barbed connectors into the nylon easier, the tube end must be soaked in a cup of boiling water for one minute immediately before pushing the barbs into the nylon. The 5/16 inch barbed connector is used for splicing 5/16 inch non-EFI and 5/16 inch EFI tubing.

4. Select the proper (1/4 or 5/16 inch) barbed connectors for completing the splice. Two connectors are required for each splice.

 CAUTION: Do not use any heating method except hot water to service nylon tubing. Temperatures above 100°C (212°F) cause the plastic to soften and it will not seal on the barbed connectors.

5. Install the barbed connectors into each end of the replacement tubing using boiling water as outlined.

6. Install clips onto any tubes which might be difficult to access once the final splices are completed.

7. Install four keystone clamps loosely onto the original nylon tubing before beginning Step 8.

8. Complete the splice of the replacement nylon to the original nylon tubing at both ends. (Use the boiling water method mentioned previously to get the required number of barbs engaged, as shown in the illustration following Step 4).

9. Tighten the clamps in the locations shown in the illustration following Step 4.

10. Install any remaining clips which were removed for this service and check that the tubes are secure in the original clips.

11. Fill fuel tank , start engine and check for leaks.

Nylon Push Connectors

NOTE: Damaged push connectors must be discarded and replaced with new push connectors. If only retaining clip is damaged, replace the clip.

1. Relieve fuel system pressure as outlined. Read cautionary note prior to relieving pressurized fuel system. If necessary, drain fuel as outlined.

2. Disconnect the damaged push connector. Be sure to bend the shipping tab to the side before removing retaining clip.

3. Select the proper size replacement push connector and nylon tube assembly. Refer to illustration showing Fuel Line Service Parts.

4. Cut out a section of the original nylon tube to the same length as the nylon tube attached to the new push connector.

   NOTE: To make hand insertion of barbed connectors into the nylon easier, the tube end must be soaked in a cup of boiling water for one minute immediately before pushing the barbs into the nylon. The 5/16 inch barbed connector is used for splicing 5/16 inch non-EFI and 5/16 inch EFI tubing. Refer to illustration following Step 4, Splicing Nylon to Nylon procedure, for all splicing service combinations.

5. Install proper barbed connector into replacement nylon assembly.

6. Install two keystone clamps loosely onto the original nylon tubing before beginning Step 7.

7. Complete the splice by connecting barbed connector to original nylon. Refer to illustration following Step 4, Splicing Nylon to Nylon procedure, for the proper barb insertion.

8. Tighten clamps in locations shown in illustration following Step 4, Splicing Nylon to Nylon procedure.

9. Connect the new connector assembly to the steel tube end.

10. Check that the underbody clips are properly securing the fuel tubes.

11. Fill fuel tank , start engine and check for fuel leaks.