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TM 5-4210-233-14&P-1
Table 4-2. Unit Troubleshooting - Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
FIREFIGHTING SYSTEM - Continued
2
ENGINE AND PUMP SPEED TOO LOW AT FULL THROTTLE
Step 1. Check that relief valve is set correctly.
Refer to Direct Support maintenance level.
Step 2. Insufficient engine power.
Engine requires maintenance; refer to Direct Support maintenance level.
3
ENGINE AND PUMP SPEED HIGHER THAN SPECIFIED FOR DESIRED PRESSURE AND VOLUME
Step 1. Check suction strainer, suction screens, or impeller vanes for debris.
Remove suction strainer and hose, and clear away all debris. Pressure backwash (preferably
in parallel or "volume" position) will usually clear impeller vanes when pump is stopped.
Step 2. Check for defective suction hose.
On old suction hoses, the inner liner sometimes becomes so rough it causes enough friction
to prevent pump from drawing full capacity. Sometimes, the liner will separate from the outer
wall and collapse when drafting. It is usually impossible to detect liner collapse, even with a
light. Try drafting with a new suction hose; if pump then delivers capacity, it may be assumed
that previous hose was defective. Replace defective hose.
Step 3. Check that suction hose correct size.
When pumping at higher than normal lifts, or at high altitudes, use a larger suction hose.
Step 4. Pump impellers or wear rings badly worn.
Refer to Direct Support maintenance level.
4
ENGINE SPEED HIGHER THAN SPECIFIED FOR DESIRED PRESSURE AND VOLUME
Check gear selection of transmission.
Ensure transmission is in "drive".
4-53
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