ISM, ISMe, and QSM11 – 006-003   Air in Fuel

Remove the fuel suction line.

Install a sight glass, Part Number 3375362, in the line.

Operate the engine.

A small air leak will have a milky appearance. A large air leak will look like bubbles in the fuel.

If an air leak is found, inspect the fuel lines, o-rings, and fittings for damage. Check for loose connections.

Replace the damaged lines or tighten the loose connections.

Operate the engine at high idle with no load, and check the sight glass.

Tighten the hose connections and the fuel filter.

Check the drop tube in the fuel tank for damage.

Replace any defective parts as required.

Remove the sight glass, and install the suction hose.

Test the engine again for other air leaks.

Remove the gear pump cooling drain line from the check valve, and install a plug in the line.

Install a hose on the check valve and place the other end of the hose in a container.

Operate the engine at high idle with no load.

If air is entering the fuel pump suction line, bubbles will be visible in the container of fuel.

If bubbles are visible, tighten the fuel supply pump inlet fitting.

Tighten the cooling plate inlet and outlet fittings.

Tighten the hose connections and the fuel filter.

Check the drop tube in the fuel tank for damage.

Correct the air leak and test again for other leaks.

Remove the hose from the check valve elbow and the plug from the cooling drain line.

Install the drain line on the check valve.