Multiquip High Pressure Centrifugal Pump (Honda GX340K1PKT2/GX340U1PKT2 Gasoline Engine) QPT305SLT - Manual (Page 19)

Qp305SLT/QpT305SLT CeNTRIFUgaL pUMp • opeRaTIoN aNd paRTS MaNUaL — Rev. #1 (10/11/10) — page 19
MaintenanCe (puMp)
pUMp vaCUUM TeST
To perform the pump vacuum test do the following:
1. Remove the pump fill cap (See Figure 2), and fill the
pump with water.
2. Start the engine as outlined in the initial start-up
section, and wait for the pump to begin pumping.
3. As shown in Figure 17, 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 suction (inlet) opening (See Figure 17) with the
vacuum gauge 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.
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 gauge. If the gauge indicates a reading
between -25 and -20 in. Hg. (inches of mercury) then
it can be assumed that the pump is working correctly.
7. If the vacuum tester gauge 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.
8. To test the flapper valve, shutdown 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.
CAUTION
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.
NOTICE
25 in. Hg (inches of mercury) translates into 25 feet of
lift at sea level.
adjUSTINg IMpeLLeR CLeaRaNCe
1. If it is necessary to replace impeller or volute, be sure
clearance between impeller and volute is adjusted
correctly.
2. The impeller should be as close to the volute as
possible without rubbing against it. Clearance is
adjusted by adding or removing shims from behind
the impeller.
3. Check clearance between impeller and insert by slowly
pulling starter rope to turn impeller. Remove spark plug
to make it easier to turn impeller.
4. Check the impeller every six months for wear, and
for clearance between the impeller face and the volute.
Also check the shaft seal for wear, as well as the shaft
sleeve.
NOTICE
QP305SLT only — It is important not to remove too
many shims or the clearance between the impeller and
volute will become too wide and pump performance
will be reduced. Remember as the impeller wear down,
additional shims may be required to maintain the
clearance between the impeller and insert.
CAUTION
The impeller may develop sharp edges. Use extreme
care when checking the impeller to prevent being cut.