Table 4-2. Unit Troubleshooting Procedures (Con"t).
TEST OR INSPECTION
While bottom loading, disconnect precheck tubing from jet level sensor (see
paragraph 4-70). Check fuel flow
in precheck tubing. Flow should
be a strong, full
If flow is a strong, full diameter flow, go to step 4.
If flow is not a strong, full diameter flow, precheck tubing is either restricted or
leaking. Go to step 3.
Compressed air used for clearing restrictions must not exceed 30 psi
(207 kPa). Wear protective clothing (goggles, face shield, and gloves) and
use caution to avoid injury to personnel.
A suitable container must be used to catch any draining fuel. Ensure that all
spills are cleaned up.
From outside of tank, disconnect precheck tubing from coupling located in tank
shell, elbows at piping assembly, and elbow at pressure gage (see paragraph 4-72).
Open precheck valve (see paragraph 2-2). If handle of precheck valve turns with
difficulty, problem may be in precheck valve. Use compressed air to clear any
restrictions in precheck tubing and to check for leaks.
If no restrictions, leaks, or damage are found, go to step 4.
If precheck tubing can be cleared of restrictions, if no leaks are found, and if
handle of precheck valve operates without difficulty, connect all precheck
If any length of precheck tubing cannot be cleared of restrictions, if leaks are
found, or if handle of precheck valve operates with difficulty, replace affected
Check for a cracked precheck can inside jet level sensor. Precheck can (smaller
inside can) should have two smaller and one larger plugged hole in bottom of can.
Check that proper holes are plugged.
If there is no damage to jet level sensor, go to step 5.