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PUMP VACUUM TEST
NOTICE
DO NOT attempt to start the engine unless the pump
has been primed with water. Severe pump damage will
occur if the pump has not been primed.
Perform the following procedure to test the pump vacuum.
Refer to Figure 19.
1. Remove the pump fill cap and fill the pump casing
with water.
WARNING
NEVER remove the fill cap while the pump is hot. Water
inside may be under pressure.
2. Start the engine as described in the Operation section,
and wait for the pump to begin pumping.
3. Place a water hose inside one of the discharge ports,
and turn on the water. The flow of water into the
discharge port will prevent the pump from running dry.
4. Place the pump vacuum tester (P/N 7000030) over the
suction port with the vacuum gauge facing upward.
It may be necessary to apply a small amount of water
around the rubber seal of the vacuum tester to create
a proper seal.
5. Make sure there are no air leaks between the vacuum
tester and the suction port. If air leaks are present,
reset the vacuum tester.
6. Run the pump for a few minutes while monitoring
the vacuum gauge. A gauge reading of 20–25 inHg
(inches of mercury) indicates that the pump is working
properly. A gauge reading below 20 inHg indicates that
the pump is not working properly.
NOTICE
25 inHg (inches of mercury) translates into 25 feet of
suction lift at sea level.
7. To test the flapper valve, shut down the engine. The
vacuum tester should remain attached to the suction
port by vacuum, indicating that the flapper valve is
seating properly and holding water in the suction hose
when the engine is stopped. This prevents backflow and
allows for faster priming when the engine is restarted.
PAGE 24 — QP4TB TRASH PUMP • OPERATION MANUAL — REV. #0 (01/11/24)
MAINTENANCE ( PUMP )
IMPELLER CLEARANCE ADJUSTMENT
Every six months, inspect the impeller, shaft seal, and
shaft sleeve for wear, and check the clearance between
the impeller and the volute. The impeller should be as close
to the volute as possible without touching it.
1. Adjust the clearance between the impeller and the
volute by adding or removing shims behind the impeller.
NOTICE
Removing too many shims will create excessive
clearance between the impeller and the volute, resulting
in reduced pump performance.
As the impeller wears down over time, additional shims
may be required to maintain minimal clearance between
the impeller and the volute.
2. Slowly pull the starter grip to rotate the impeller just
a bit. Repeat this a few times while checking the
clearance between the impeller and the volute.
If it becomes necessary to replace the impeller or the
volute, make sure the clearance between the impeller and
the volute is adjusted correctly.
PUMP CLEANING
After pumping water with a large quantity of dirt and debris,
perform the following procedure to clean out the pump:
1. Remove the drain plug from the pump housing to drain
any water remaining in the pump.
2. Loosen the four locking knobs by turning them
counterclockwise. Grip the clean-out cover handles,
twist counterclockwise, and pull outward to open the
clean-out cover.
3. Clean inside the pump casing and remove all dirt
and debris. Inspect the impeller and volute for wear.
Replace any damaged or worn parts.
CAUTION
The impeller can develop sharp edges. BE CAREFUL
when cleaning around the impeller to prevent injury.
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