20
Maintenance
Troubleshooting
Problem
Possible Cause
Solution
Low Operating
Pressure
Faulty pressure gauge
Install new gauge.
Insufficient water supply
Use larger garden hose; clean filter washer at water
inlet.
Old, worn or incorrect spray
nozzle
Match nozzle number to machine and/or replace with
new nozzle.
Plumbing or hose leak
Check plumbing system for leaks. Retape leaks with
teflon tape.
Faulty or mis-adjusted unloader
valve (where applicable)
Adjust unloader for proper pressure. Install repair kit
when needed.
Worn packing in pump
Install new packing kit.
Fouled or dirty inlet or discharge
valves in pump
Clean inlet or discharge valves.
Worn inlet or discharge valves
Replace with valve kit.
Detergent Not
Drawing
Air leak
Tighten all clamps.
Check detergent lines for holes.
Valve in the injector head may be
blocked, dirty or damaged
Clean or replace valve in injector.
Filler screen on detergent suction
hose plugged
Clean or replace.
Dried up detergent plugging
metering valve
Disassemble and clean thoroughly.
High viscosity of detergent
Dilute detergent to specifications.
Hole in detergent line(s)
Repair hole.
Low detergent level
Add detergent if needed.
Discharge water temperature
above 180°F
Lower discharge water temperature.
Pump Running
Normally but Pressure
Low on Installation
Pump sucking air
Check water supply and possibility of air seepage.
Valves sticking
Check and clean or replace if necessary.
Unloader valve seat faulty
Check and replace if necessary.
Nozzle incorrectly sized
Check and replace if necessary (See serial plate for
proper size).
Worn piston packing
Check and replace in necessary.
Fluctuating Pressure
Valves worn
Check and replace if necessary.
Blockage in valve
Check and replace if necessary.
Pump sucking air
Check water supply and air seepage at joints in
suction line.
Worn piston packing
Check and replace if necessary.
Pump Noisy
Air in suction line
Check water supply and connections on suction line.
Broken or weak inlet or discharge
valve springs
Check and replace if necessary.
Excessive matter in valves
Check and clean if necessary.
Worn bearings
Check and replace if necessary.
Kärcher HPB Series Operator’s Manual 9.801-190.0 - W
