Table 4-2. Unit Troubleshooting Procedures (Con't).
TEST OR INSPECTION
An inadequate flow is defined as a flow that is not a strong, full diameter
flow. An adequate flow will fill a gallon container at least half full within
approximately one minute.
If there is no flow, or if flow is inadequate, or full of air and spitting, problem is in
jet level sensor or in jet level sensor tubing. Go to step 3.
If there is an adequate steady flow of fuel, problem is NOT in jet level sensor or
in jet level sensor tubing. Problem is in emergency valve. Remove emergency
valve and repair. Be sure to replace all preformed packings (see paragraph
Remove jet level sensor (see paragraph 4-70). Inspect jet level sensor for restricted
orifices or for other damage. Look for dirt or other contaminants clogging the two
Clean jet level sensor and remove any dirt or other contaminants that are
clogging the orifices. If jet level sensor is damaged, obtain a replacement.
Install jet level sensor, but leave jet level sensor tubing disconnected (see
If jet level sensor orifices are not restricted and no other damage is observed,
problem is in tubing between emergency valve and jet level sensor. Install jet
level sensor, but leave jet level sensor tubing disconnected (see paragraph
Compressed air used for clearing tubing must not exceed 30 psi (207 kPa).
Wear protective clothing (goggles, face shield, and gloves) and use caution
to avoid injury to personnel.
At emergency valve, remove nut from bleeder valve. Tag and disconnect all jet level
From emergency valve end, force clean compressed air into all tubing lengths. Have
an assistant positioned at jet level sensor end. Assistant should hold a clean rag
(Item 18, Appendix E) against ends of tubing as air is forced through and should look
for signs of escaping dirt or other contaminants. Assistant should also check that air
flow through tubing indicates that tubing is free of restrictions or leaks.
If jet level sensor tubing can be cleared with compressed air, connect tubing at
jet level sensor. Install nut at bleeder valve and connect jet level sensor tubing
If jet level sensor tubing cannot be cleared or air flow through tubing indicates a
restriction or a leak, perform a visual inspection of tubing between jet level
sensor and emergency valve inside tank. Replace damaged tubing (see