TM 5-3805-293-23-2
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AIR-IN-FUEL TEST CONTINUED
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27. Run engine at 2000 rpm for 2 minutes (TM 5-3805-293-10).
28. Monitor site tube for air bubbles.
a. There should be no air bubbles in sight tube, however small bubbles that are spaced more than 1.0 inch
(2.5 cm) apart are acceptable. Proceed to step 29.
b. Presence of large bubbles or a continuous stream of bubbles indicates a leak before the primary fuel
pump.
(1) Inspect low pressure fuel lines (Figure 28, Items 1 and 2) for wetness or dripping fuel between fuel
tank and inlet at primary fuel pump. If condition found, replace fuel line (WP 0173).
(2) Inspect primary fuel filter base (Figure 28, Item 3) for cross threaded or stripped connections. If
condition found, replace fuel filter base (WP 0174).
Figure 28. Primary Fuel Filter Base.
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