Table 4-2. Unit Troubleshooting Guide (Continued)
TEST OR INSPECTION
6. Booster pump is started in "CLEAN" mode but ROWPU shuts down on low feed pressure when the high pressure
pump is started.
Check inlet of booster pump for clogging.
Remove object clogging pump (para. 4-43).
7. Booster pump motor hums but wont turn.
Death or injury may result if the booster pump circuit breaker is not turned off before
performing the next step.
Remove access panel and turn shaft between pump and motor.
(a) If the shaft turns, refer to booster pump electrical troubleshooting (malfunction 4).
(b) If the shaft will not turn, there is a foreign object in the pump housing. Replace the pump and
motor assembly (para. 4-43).
If the unit is operating in cold weather conditions, the pump may have ice in the
impeller due to not being drained. Use an external pump heater to thaw the pump
8. Booster pump does not deliver enough pressure or feed flow to operate ROWPU.
Step 1. Check pump for operation. Remove access cover and visually check that pump is running.
If pump is not running, refer to booster pump electrical troubleshooting (malfunction 1, 2, 5, or 6).
Step 2. Refer to "high pressure pump" troubleshooting (malfunction 14).
Step 3. Check the booster pump inlet for plugging.
(a) Remove object plugging pump.
(b) Replace the booster pump (para. 4-43) if troubleshooting done in Step 2 and raw water pump
troubleshooting indicates that the booster pump is the only item Ieft that could cause the problem.
When deciding to replace booster pump, take into account that 90% of the problems
that cause these symptoms are related to the raw water system which takes the most
abuse and the raw water pump in particular, as it will wear away internally due to
sand erosion. The wear that causes these problems only shows up when the pump is
operating at full flow rate or during disassembly.
Basket strainer plugged light is on and strainer is clean or, basket strainer plugged light has not come on and strainer is
Operate the unit and determine that the malfunction is true.
Notify direct support maintenance to troubleshoot the strainer differential pressure switch circuits.