Multiquip MQ41TDH - Manual (Page 21)

MQ41TDH TRASH PUMP — PARTS & OPERATION MANUAL — REV. #3 (04/02/07) — PAGE 21
MQ41TDH — MAINTENANCE
Pump Vacuum Test
CAUTION :
To perform the pump vacuum test do the following:
1. Remove the pump fill cap, and fill the pump with water.
2. Start the engine as outlined in the initial strat-up section,
and wait for the pump to begin pumping.
3. As shown in Figure 12 (next page), place a water hose
inside the discharge opening of the pump, and turn on
the water. This flow of water into the discharge opening
will
prevent the pump from running dry.
4. Place the Pump Vacuum Tester (P/N 7000030) over
the pump inlet opening (Figure 15) with the vacuum guage
facing upwards. It may be necessary to apply a small
amount of water around the rubber seal of the vacuum
tester to make a good suction fit.
DO NOT attempt to start the engine unless the
pump has previously been
primed . with water.
Severe pump damage will occur if pump has
not been primed.
5. Check and make sure that there are no air leaks between
the vacuum tester and the inlet port on the pump. If air
leaks are present reseat vacuum tester.
6. Run the pump for a few minutes while monitoring the
vacuum guage. If the guage indicates a reading between
-25 and -20 in. Hg. (inches of mecury) then it can be
assumed that the pump is working correctly.
7. If the vacuum tester guage indicates a reading
below -20 in. Hg, it can then be assumed that the pump
is not functioning correctly, and corrective action needs
to be taken.
6. To test the flapper valve, shut down the engine. The
vacuum tester should remain attached to the pump
suction inlet port by vacuum. This indicates the pump's
flapper valve is seating properly to hold water in the
suction hose when the engine is stopped. This prevents
backflow and allows for faster priming when the engine
is restarted.
NOTE
25 in. Hg (inches of mecury) translates
into 25 feet of lift at
sea level.