Table 5-2. Direct Support Troubleshooting - Continued
TEST OR INSPECTION
FIREFIGHTING SYSTEM - Continued
PUMP FAILS TO PRIME OR LOSES PRIME - Continued
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).
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
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.