10c. Fuel Aeration Test

10c. FUEL AERATION TEST

Purpose
To determine if the fuel is aerated and causing a poor idle condition.

Fuel Aeration Test
Install a clear hose on the fuel return line at the fuel conditioning module.

Run the engine at WOT for 2 minutes.

The return fuel should be free of bubbles.







1. Remove the fuel return line at the fuel conditioning module.
2. Attach a 1/4 inch diameter hose (clear) to the fuel conditioning module and place the other end of the hose into Rotunda Tool 034-00005 or equivalent.
3. Turn the ignition to the ON position. The fuel pump cycles on, then off. Diesel fuel may not flow out through the attached hose after only one ignition cycle. Repeat the ignition cycle until fuel flows from the attached hose.
4. Start the engine.
5. Run at WOT for 2 minutes. Return fuel should be free of bubbles.
6. If the fuel has air in it, the fuel returning to the tank appears white, foamy or non-transparent. If no or very little air is present in the fuel, the fuel will appears clear/transparent.
7. If air is present in the return fuel, inspect the fuel system for leaks.

Possible Causes:

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.

Tools Required:
Rotunda Tool 034-00005 or equivalent