MQD2H/3H DIAPHRAGM PUMP • OPERATION MANUAL — REV. # 8 (07/31/20) — PAGE 27
Table 8. Engine Troubleshooting
Symptom
Possible Problem
Solution
Operation not satisfactory
Rotational speed fluctuates.
Governor adjustment improper?
Adjust governor to correct lever.
Governor spring defective?
Clean or replace ignition.
Fuel flow erratic?
Check fuel line.
Air taken in through suction line?
Check suction line.
Recoil starter not working properly.
Dust in rotating part?
Clean recoil starter assembly.
Spring failure?
Replace spiral spring.
TROUBLESHOOTING (ENGINE/PUMP)
Table 9. Pump Troubleshooting
Symptom
Possible Problem
Solution
Pump does not take
on water.
Not enough priming water in the housing?
Add water to suction chamber.
Engine speed too low?
Increase throttle.
Strainer plugged?
Clean strainer.
Suction hose damaged?
Replace or repair hose, and clamps.
Air leak at suction port?
Check that fittings are tight and properly
sealed.
Pump is located too high above water line? Move pump closer to water.
Debris collecting in pump housing?
Clean pump housing.
Valves not seated correctly?
Check that valves are seated correctly.
Pour water in in suction chamber to help
seal valves.
Pump does not prime correctly?
Check diaphragm for breaks or leaks.
Pump takes in water, little or
no discharge.
Engine speed too low?
Increase throttle speed.
Suction hose leaks at inlet?
Clean strainer.
Suction hose leaks at inlet.
Teflon Tape/Pipe Dope not used?
Apply teflon tape or pipe dope to NPT
fittings.
Hose diameter is too large?
Use smaller diameter hose or replace
hose.
Discharge does not stay on
coupling.
Pressure too high?
Check pressure, add additional clamp.
Hose kinked or end blocked?
Check hose.
