Materials
Fuel Lines – These are welded steel tubes, meeting GM Specifications 124-M, or its equivalent. Do not use copper or aluminum tubing to replace steel tubing.
Those materials do not have satisfactory durability to withstand normal vehicle vibration.
Coupled hose – These are not to be repaired and are replaced only as an assembly.
Uncoupled Hose – Use only reinforced furl resistant hose, made of Fluoroelastomer material. Do not use a hose within 4 inches (100 mm) of any part of the exhaust system, or within 10 inches (254 mm) of the catalytic converter. The hose inside diameter must match the outside diameter of the steel tubing.
Clamps – These are stainless steel, screw bank-type clamps, #2494772, or equivalent.
Fuel Pipe Repair
1. Cut a piece of fuel hose 4 inches (100 mm) longer than the section of pipe to be removed. If more than 6 inches (152 mm) is to be removed, use a combination of steel pipe and hose. The hose length should not be more than 10 inches total.
2. Cut a section of the pipe to be replaced with a tube cutter. Use the first step of a double flaring tool to form a bead on the ends of the pipe and, also, on the new section of pipe, if used.
3. Slide the hose clamps onto the pipe and push the hose 2 inches (51 mm) onto each portion of the fuel pipe. Tighten a clamp on each side of the repair.
4. Secure the fuel line to the frame.
Fuel System Cleaning
Removal Procedure
Caution: Refer to Battery Disconnect Caution in Cautions and Notices.
1. Remove the negative battery cable(s).
2. Remove the fuel from the tank. Refer to Fuel Tank Draining Procedure.
3. Remove the fuel tank.
4. Remove the fuel sender. Refer to Fuel Sender Assembly Replacement.
5. Clean the fuel tank.
Important: The fuel tank should be replaced if the tank is rusted internally.
6. Remove the fuel strainer or replace if necessary.
Refer to Fuel Sender Assembly Service.
7. Remove the fuel feed hose at the fuel lift pump.
8. Remove the fuel return line at the injection pump.
โข Use low air pressure to blow out the lines toward the rear of the vehicle.
โข Replace the pipes if they are rusted internally.
9. Remove the ECM 1 fuse from the underhood relay center.
10. Remove the fuel filter. Refer to Fuel Filter Element
Replacement.
Installation Procedure
1. Install the fuel sender. Refer to Fuel Sender Assembly Replacement.
2. Install the fuel tank.
3. Install the fuel feed pipes at the fuel lift pump.
4. Install clean diesel fuel into the tank until it is V a full.
5. Install the fuel tank cap.
6. Install the negative battery cables.
7. Crank the engine for 15 seconds with one minute cooling periods until the clean fuel is pumped out.
Important: Use a suitable container to catch the fuel.
8. Install a new fuel filter. Refer to Fuel Filter Element Replacement.
9. Install a hose from the return line at the fuel injection pump to a closed metal container with a capacity of at least 8 liters (2 gallons).
10. Crank the engine for 15 seconds with one minute cooling periods until clean fuel appears at the return line.
11. Install the ECM 1 fuse in the underhood relay center.
โข Crack open each injection line at the nozzle.
Use two wrenches to prevent nozzle damage.
โข Crank the engine for 15 seconds with one minute cooling periods until clean fuel appears from each nozzle.
Notice: Refer to Fastener Notice in Cautions and Notices.
Important: Use two wrenches to prevent nozzle damage.
โข Retighten the injection line fittings.
Tighten
Tighten the injection line to nozzle fitting to 25 N-m (18 lb ft).
โข Start the engine and allow it to idle for 15 minutes.
Important: Make sure the fuel return line is in the metal container and that the container does not overflow.
โข Remove the hose from the metal container.
12. Install the fuel return line to the injection pump.
13. Check for leaks.
14. Clear any engine DTCs.
Gasoline in Fuel System
Engine Will Run or Start
1. Drain the fuel tank. Refer to Fuel Tank Draining Procedure.
2. Fill the fuel tank with diesel fuel.
3. Run the engine for 15 minutes.
Engine W il l Not Run
1. Drain the fuel tank. Refer to Fuel Tank Draining Procedure.
2. Fill the fuel tank with diesel fuel.
3. Remove the ECM 1 fuse from the underhood relay center.
4. Remove the fuel hose between the fuel manager/filter and the injection pump.
5. Connect a hose to the fuel manager/filter outlet and run it to a closed metal container.
6. Crank the engine for 15 seconds with one minute cooling periods to purge the gasoline from the system.
7. Install the fuel hose between the fuel filter and the injection pump.
8. Install the ECM 1 fuse in the underhood relay center.
9. Start the engine.
Important: Check for leaks.
10. Run the engine for 15 minutes.
11. Clear the engine DTCs.
Fuel Feed and Fuel Return Pipe Purge
Procedure
1. Open the air bleed valve on top of the fuel manager/filter.
2. Connect a hose to the air bleed valve located on top of the fuel manager/filter and place the other end of the hose into a suitable container.
3. Remove the ECM 1 fuse from the underhood relay center.
4. Crank the engine in 10 to 15 second intervals until clear fuel is observed at the air bleed hose (wait for one minute between cranking intervals to cool down starter motor).
5. Close the air bleed valve.
6. Install the ECM 1 fuse in the underhood relay center.
7. Start the engine and allow to run for 5 minutes at idle.
8. Check for fuel leaks.
9. Clear all engine DTCs.
