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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
5
INSUFFICIENT PRESSURE
Step 1. Follow procedures for engine and pump speed higher than specified for desired pressure
and volume.
Step 2. Check pump speed with tachometer at RPM COUNTER connection on pump operator's
panel. If pump speed is too low, adjust throttle. If proper engine speed cannot be maintained,
refer to engine troubleshooting.
CAUTION
Do not attempt to pump greater volume of water at the desired
pressure than the pump is designed to handle. Exceeding
pump capacity will reduce pressure in an inverse ratio.
Exceeding maximum recommended pump speed will produce
cavitation, and will seriously impair pump efficiency.
6
PRESSURE NOT RELIEVED WHEN DISCHARGE VALVES ARE CLOSED
Step 1. Check for sticky pilot valve.
Repair pilot valve (see para 4-36).
Step 2. Check for plugged lines.
Remove obstruction or replace line.
7
PRESSURE WILL NOT RETURN TO ORIGINAL SETTING AFTER DISCHARGE VALVES ARE RE-
OPENED
Step 1. Check for sticky pilot valve.
Repair pilot valve (see para 4-36).
Step 2. Check for main relief valve sticking.
Repair relief valve (see para 4-35).
4-54
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