Bleeding a GM 6.2 diesel fuel system purges air from the fuel lines between the fuel tank and the injection pump. Air sometimes enters the fuel system following replacement of fuel filters or when fuel lines and connections are broken or leaking. GM modified this fuel system several times during the period of manufacture--from 1982 to 1993--so be sure you can identify all of the components in your own engine's fuel system before beginning.
Instructions
Identify Your GM 6.2 Diesel Fuel System Components
1. Check what year your engine was manufactured. You can do this by checking your insurance papers, or look on the post on the driver's side door where you will find a metal printed tag that states the year of manufacture and other information like engine size and type.
2. If your engine was manufactured in 1982 or 1983, it will have a spin-on primary fuel filter mounted on the firewall. The secondary filter is either a spin-on type mounted on the back of the intake manifold or a box-type filter on the intake manifold.
3. If your diesel engine was manufactured in 1984 or later, it has only one fuel filter mounted on the firewall. This box-type filter has fuel inlet and outlet ports, an air bleed valve to allow release of air and retaining clips to hold the filter in place. This filter assembly heats fuel, separates water and dirt from the fuel and has a filter change signal device built in as well.
Bleeding 1982 and 1983 GM 6.2 Diesel Engines
1. Fill the primary filter up with clean diesel fuel and screw it into place, giving it three-quarters of a turn after the gasket touches the metal ring. If there are no other leaks or changes in your fuel system, you can start the motor at this point and let it run to purge any last air from the top filter.
2. To bleed the rest of the fuel system, you must now bleed the secondary filter as well. Remove the air filter assembly and locate the secondary filter on the intake manifold.
3. Disconnect the pink wire from the fuel injection pump to prevent the engine from starting when you crank it.
4. Put a rag under the fuel outlet on the secondary filter and crank the engine for 10 seconds or less until fuel flows from the outlet. If no fuel comes out, let the engine sit for 15 seconds and crank it again. When fuel flows out, connect the fuel line to the outlet and tighten it.
5. Connect the pink wire back to the fuel injector, start the engine and let it idle. This will purge any remaining air in the fuel system.
6. Be sure to check all the fuel lines, filters and connections for leaks.
