Table 5-2. Direct Support Troubleshooting-continued -706880692

TM 5-4210-233-14&P-1

Table 5-2. Direct Support Troubleshooting - Continued

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

FIREFIGHTING SYSTEM - Continued

PUMP FAILS TO PRIME OR LOSES PRIME - Continued

NOTE

Oil the priming pump after each operation in accordance

with the lubrication instructions.

Step 4. Defective priming motor solenoid.

Refer to electrical troubleshooting procedures (see Chapter 4).

ENGINE AND/OR PUMP SPEED TOO LOW AT FULL THROTTLE

Step 1. Insufficient power.

Engine requires maintenance (see Chapter 6).

Step 2. Relief valve set improperly.

Adjust relief valve (see para 2-13).

NOTE

If relief valve is set to relieve below desired operating

pressure, water will bypass and reduce capacity.

ENGINE AND PUMP SPEED HIGHER THAN SPECIFIED FOR DESIRED PRESSURE AND

VOLUME

Pump impellers or wear rings badly worn.

Install undersize wear rings if impeller to wear ring clearance is within limits indicated in

MAINTENANCE INSTRUCTIONS. If not, install new impellers and wear rings (see para 6-6).

PRESSURE NOT RELIEVED WHEN DISCHARGE VALVES ARE CLOSED

Step 1. Pilot valve sticking.

Disassemble and clean (see para 4-36). Replace noticeably worn parts.

Step 2. Incorrect assembly or plugged tube lines.

Disconnect lines and inspect. Check to be sure the drain valve is sealing correctly and

not bypassing water.

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