Introduction
In nearly all instances, pump failure is the result of improper installation or operation rather than normal wear. One of the most common causes of pump failure is improper or unnecessary service, often as a result of the operator attempting the service.
Each time the pump is serviced, the chance of pump failure as a result of improper service increases. The operator should be left with no reason or desire to open the pump for service.
Usually requests for service are not made until the operation of the equipment has become so bad that it usually does not work.
The high pressure pump is generally one of the most dependable and best constructed components in a high pressure cleaner. The well-engineered pump may be installed in a not-so-well engineered system. All pumps have wear parts, which eventually need to be replaced.
In most cases, the high pressure pump is likely to outlast most other components as long as the pump is installed correctly and the system is operated properly. (This is a quote from The Universal Guide to High Pressure and Steam Cleaner Repair.)
Pump chattering caused by heavy cavitation can be mistaken for a broken connecting rod. To determine if cavitation is the source of the problem, open the upstream chemical injector completely while operating the system. If the noise leaves it is cavitation. If the system does not have an upstream injector hook up a positive feed system to the pump and operate the system.
Do not assume that the pump is the problem.
Set up a check list.
| Excessive noise: |
Hot water |
Mounting bolts |
| |
Cavitation |
Vibrations in the system |
| |
Worn valves |
Worn O-rings |
| |
Belts |
Connecting rods |
| |
Pulleys |
Plunger rod pins |
| |
Bearings |
|
| Oil leaks: |
Bad seals |
| |
Red shipping cap has no been removed |
| Loss of pressure: |
Worn nozzle |
Packings |
| |
Bad pressure gauge |
Valve seat O-rings |
| |
RPM |
Inlet pressure or flow |
| |
Valves |
|
|
How to Start
Ask the Right Question At the Right Time
Isolate the Problem
Set Up a Diagnostic Procedure
Simple to Hard
Logical Progression
Use Simple Tools
Eyes
Ears
Nose
Brain
Start With Observations
Physical Inspection and Observations
Carefully Observe the Equipment In Operation
Trace the Fluid Flow
Disregard False Impressions
Dont Skip Any Steps
Start At Point A and Finish at Point Z
Isolate the Problem
Remember, Problems Can Cause Problems
Pump Failures: There Are Several Reasons for Pump Failure, and Most Are Generally Connected with
Improper Use
Insufficient or Dirty Water
Plugged Filters
Kinked or Plugged Hoses
Cavitation
Lack of Maintenance
Fluid System
NO FLOW:
No Power to the Pump
Trigger Gun Not Opening
No Water Source
Clogged Spray Nozzle
Clogged Inlet Filter
Stuck Float Valve
Faulty Unloader
Pinched or Clogged Inlet Hose
Inlet Valve(s) Not Open
LOW PRESSURE, ADEQUATE FLOW:
Worn, Incorrect, No Spray Nozzle
Lance on Low Pressure Setting
Unloader/Regulator Improperly Adjusted
Pressure Gauge Inaccurate or Broken
Worn Pump Packings
LOW PRESSURE, LOW FLOW:
Volume Improperly Adjusted
Discharge Leaks
Chemical Injector Orifice Blocked
Drive Belts Loose
Pump or Motor Not Running at Rated Speed
Stripped Pump Drive Coupling
Defective Easy Start Valve
Malfunctioning Motor or Engine
LOW PRESSURE, VERY LOW FLOW:
Unloader Stuck In Bypass
Outlet Restriction
Clogged Nozzle
Restriction in the High Pressure Hose
Debris in the System
Cavitation
Clogged Inlet Hose or Filter
EXCESSIVE PRESSURE:
Spray Nozzle Too Small
Faulty Pressure Gauge
Unloader/Regulator Improperly Adjusted
Faulty Unloader/Regulator
PUMP CHATTERS:
Air in the System
Chemical Line Not Submerged
Inlet Line Kinked, Restricted, or Internal Hose Separation
Inadequate Water Supply
Float Valve Is Stuck
Turbulence in the Float/Supply Tank
Cavitation
Inlet or Inlet Strainer Clogged
Water Supply Too Hot
INLET LINE VIBRATION:
Air in the System
Debris in the Valves
OUTLET LINE VIBRATES:
Air in the System
Debris in the Discharge Valves
Damaged Pump Packings
INLET & OUTLET LINES VIBRATE:
Inlet and/or Discharge Valves Fouled
Other Downstream Restrictions
Air in the System
UNLOADERSIREGULATORS VERY LOW OR NO FLOW:
Unloader Stuck In Bypass
UNLOADER CYCLES WITH SYSTEM UNDER PRESSURE (FLOW UNLOADER):
Improper Flow
Nozzle Too Small
Nozzle Clogged
Improper Unloader Orifice
Unloader Orifice Clogged
Injector Orifice Clogged
UNLOADER CYCLES WITH THE SYSTEM IN BYPASS (FLOW UNLOADER):
No Restriction in the Unloader
Weep Gun in the System
Downstream Leakage
Accumulator Downstream
UNLOADER PRODUCES SMOOTH FLOW & LOW VOLUME (TRAP UNLOADER):
Unloader Adjusted Too Low
Spray Nozzle Clogged
Spray Nozzle Too Small
Injector Orifice Blocked
UNLOADER PRODUCES SMOOTH FLOW & LOW VOLUME (FLOW UNLOADER):
Unloader Adjusted Too Low
Unloader Is Stuck in Bypass
Restriction in the System
UNLOADER PRODUCES LOW FLOW & NORMAL PRESSURE (TRAP UNLOADER):
Nozzle Too Small
UNLOADER PRODUCES LOW FLOW & NORMAL PRESSURE (FLOW UNLOADER):
Nozzle Too Small
UNLOADER PRESSURE INCREASES WHEN THE TRIGGER IS RELEASED (FLOW):
Unloader Piston is Stuck or Frozen
Bypass Port Is Clogged or Restricted
Excessive Tension on the Main Spring
LEAKING:
Leaking from the Inlet:
Bad Inlet Hose Seal
Loose Clamps or Connections
Leaking from the Float Tank:
Float Is Full of Water or Stuck
Leaking from the Pressure Fittings:
Fittings Not Tightened or Sealed
Leaking from the Quick Disconnects:
Bad O-Ring
Leaking from the Pump:
Bad Low Pressure Seal(s)
Cracked Plunger
Damaged Manifold
Leaking from the Trigger Gun:
Bad Piston O-Ring
Stripped Connection
Leaking from the Nozzle:
Weep Gun
Damaged Gun Valve Ball & Seat
Leaking from the Pop Off Valve:
System Over Pressure
Clogged Nozzle
Trigger Gun Not Working
Excessive Pressure Spikes
Wear on the Ball & Seat
Trigger Gun
NO FLOW FROM THE NOZZLE WHEN THE TRIGGER IS DEPRESSED:
Broken Rod in the Trigger Gun
Blockage in the System Past the Trigger Gun
EXCESSIVE PRESSURE WHEN THE TRIGGER GUN IS RELEASED:
Excessive Pressure Spike
Malfunctioning Unloader
FLOW DOES NOT STOP WHEN THE TRIGGER IS RELEASED:
Broken Return Spring
Debris in the Gun Valve
TRIGGER ACTION STICKS:
Keeper Is Too Tight
Chemical System
NO CHEMICAL:
Chemical Valve Is Closed
Chemical Foot Strainer Is Clogged
Chemical Line Is Kinked
No Adjustment for Low Pressure
Chemical Nozzle Not Sized Properly
Wrong Size Chemical Orifice
EXCESSIVE CHEMICAL:
Valve Improperly Adjusted
SPRAY NOZZLE:
Spray Pattern Irregular.-
Clogged Nozzle
Worn Nozzle
Volume Proper, Pressure Low.-
Nozzle Is Too Large
Internal Nozzle Wear
Pressure Proper, Volume Low.-
Clogged Nozzle
OIL BETWEEN THE CRANKCASE AND PUMP MANIFOLD:
Worn Plunger Rod Oil Seals
OIL LEAKING IN THE CRANKSHAFT AREA:
Worn Crankshaft Oil Seal
Bad Bearings
EXCESSIVE PLAY IN THE CRANKSHAFT PULLEY AREA:
Worn Bearings from Excessive Belt Tension
OIL FROM UNDER THE CRANKCASE:
Leaking Plunger Rod, Side Cover, Rear Cover, or Crankshaft Oil Seals Or O-Rings
LOUD KNOCKING NOISE IN THE PUMP:
Pulley Loose on the Crankshaft
Broken Or Worn Bearing, Connecting Rod, Or Plunger Rod
Cavitation
FREQUENT OR PREMATURE PACKING FAILURE:
Scored, Damaged, or Worn Plunger
Overpressure to the Inlet Manifold
Abrasive Material in the Fluid Being Pumped
Excessive Pressure and/or Temperature of the Fluid Being Pumped
Pump Running Dry
Cavitation
HIGH CRANKCASE TEMPERATURE:
Wrong Oil
Low Oil Level
Old Oil
Contaminated Oil
Oil Breakdown
WATER IN THE CRANKCASE:
Worn Low Pressure Seals
Cracked Plunger
Worn Plunger Rod O-Ring
Humid Air Condition
Water Running Over The Pump 
