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

Test

TOC

Sight Glass Method


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.

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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.

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

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Tighten the hose connections and the fuel filter.

Check the drop tube in the fuel tank for damage.

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Replace any defective parts as required.

Remove the sight glass, and install the suction hose.

Test the engine again for other air leaks.

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Gear Pump Drain Method


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.

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Operate the engine at high idle with no load.

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

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

Tighten the cooling plate inlet and outlet fittings.

 
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Tighten the hose connections and the fuel filter.

Check the drop tube in the fuel tank for damage.

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Correct the air leak and test again for other leaks.

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

Install the drain line on the check valve.

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Last Modified:  23-Jan-2009