Air In Fuel Test

NOTE: Air can enter the fuel system at any point where there is suction in the fuel system.
^ Fuel pickup in the fuel tank.
^ Fuel supply line entering the fuel module from the fuel tank.
^ Fuel return line entering the fuel module from the engine.

1. Remove the fuel return line.
2. Attach a 1/4-inch diameter hose (clear) to the fuel pump module and place the other end of the hose into Rotunda tool 034-00005 or the equivalent.
3. Turn the ignition on. The fuel pump will cycle on, then off. Diesel fuel may not flow out through the attached hose after only one key cycle. Repeat the key cycle until fuel flows from the attached hose.
4. Start the engine.
5. If the fuel has air in it, the fuel returning to the tank will appear white, foamy or non-transparent. If no or very little air is present in the fuel, it will appear clear/transparent.