Troubleshooting: common problems and solutions


Despite the complexity of your industrial power washing equipment, a number of common complaints stem from relatively simple problems. With guidance, the user can identify and remedy many common power washer problems.

Cold Water Pressure Washer Troubleshooting

Always disconnect the power supply before attempting to service any power washing equipment.




Pressure washer will not run -Switch in ‘off’ position
-Machine not plugged in
-GFCI tripped
-Overload on motor tripped
-Circuit breaker tripped
-Turn switch to ‘on’ position
-Plug machine into adequate service
-Reset GFCI
-Allow automatic overload to cool or push the reset button located on motor to reset
-Reset circuit breaker in main panel
Unit runs but no water discharges -Water supply not turned on
-Plugged nozzle on wand
-Trigger gun off or malfunctioning
-Turn on water supply
-Remove, clean, or replace nozzle
-Remove, repair, or replace trigger gun
Low nozzle pressure -Plugged spray nozzle
-Inlet screen is plugged
-Insufficient water supply
-Unloader valve stuck open
-Plugged inlet or discharge hose
-Use of additional lengths of hose
-Remove nozzle and clean or replace
-Remove filter and clean or replace
-Secure adequate water supply
-Disassemble and clean; repair or replace
-Flush or replace hoses
-Reduce discharge hose length.
Surging pressure or drop in pressure -Partially plugged spray nozzle
-Worn nozzle
-Soap (low pressure tip installed)
-Restricted or leaking water hose
-Cavitation (inadequate water supply)
-Worn pump packings
-Fouled inlet or discharge valves
-Broken valve spring
-Worn or restricted unloader valve
-Remove nozzle and clean or replace
-Remove and replace nozzle
-Remove and install one of the nozzles
-Check inlet hose and filter; clean or replace
-Secure adequate water supply
-Inspect and replace worn packings
-Inspect valves and clean or replace
-Inspect and replace valve spring
-Inspect unloader and repair or replace
Pressure at pump but low discharge pressure at gun -Restricted discharge -Check for discharge obstructions in injector, hose, wand, and unloader
Chemical injector not working properly
-Valve on gun/wand not open
-Injector valve not turned on
-Discharge hose too long
-Clogged injector pick-up hose
-Clogged injector
-Open valve by turning forward handle counterclockwise.
(see wand breakdown page 10)
-Turn on injector by turning fitting on injector
-Reduce hose length or reposition injector to within forty feet of trigger gun
-Remove and clean or replace
-Disassemble, clean, and reassemble
Water leaks from pump manifold
-Worn plungers or packings
-Inspect and replace
Unloader does not bypass
-All valves fouled
-Unloader valve seat fouled
-Inspect valves and clean or replace
-Inspect and clean or replace
Unloader cycles when gun is shut off
-Leak in trigger or discharge
-Inspect leaking fittings and repair or replace
Water in crankcase
-High humidity or direct water spray
-Worn seals
-Reduce oil change intervals
-Replace seals

Hot Water Pressure Washer Troubleshooting




Will not produce hot water -Burner switch in ‘off’ position
-Burner switch on but pump switch off
-Inadequate fuel supply
-Plugged fuel filter
-Trigger gun not pulled on
-Thermostat turned off
-Turn burner switch on
-Turn on pump switch (must be on for heater to operate properly)
-Fill tank with kerosene, no. 1 or no. 2 diesel
-Replace fuel filter
-Pull trigger gun (water flow must go through coil to operate heater)
-Turn thermostat dial to the ‘on’ position
Low Water Pressure

-Insufficient water source
-Old or incorrect nozzle
-Plumbing or hose leak
-Obstruction in spray nozzle
-Chemical valve open
-Unloader valve worn
-Pump valves dirty or worn

-Check hose size/water source
-Replace nozzle
-Tighten, repair or replace leak
-Clean or replace nozzle
-Close valve or submerge hose
-Replace unloader
Clean or replace packing valves
No Chemical Flow
-Detergent valve closed
- Low detergent level
-Chemical screen dirty
-Open detergent valve
-Fill detergent container
-Clean detergent screen
Burner Not Igniting
-No fuel
-Burner switch turned off
-Thermostat set too low
-Clogged fuel filter
-Defective pressure switch
-Clogged burner nozzle
-Fuel pump malfunction
-Improper electrode setting
-Fill fuel tank with proper fuel
-Turn burner switch on
-Reset thermostat
-Replace fuel filter
-Replace pressure switch
-Replace burner nozzle
-Replace fuel pump
-Clean/reset to specifications
Excessive Burner Smoke
-Improper fuel being used
-Water contamination in fuel
-Improper air band adjustment
-Low fuel pressure
-Air leaks in fuel lines
-Soot on coils/burner assembly
-Misaligned electrodes
-Dirty burner nozzle
-Use diesel #1/#2 or Kerosene
-Drain fuel and replace with new
-Readjust air band/altitude
-Adjust to specifications
-Check for air leaks or bubbles
-Clean coil/burner assembly
-Realign to specifications
Clean or replace burner nozzle
Pressure Relief Valve Leaks
-Nozzle is dirty
-Defective relief valve
-Unloader adjusted incorrectly
-Restriction on discharge hose
-Scale restriction flow in coil
-Clean or replace nozzle
-Replace relief valve
-Adjust unloader valve
-Remove nozzle and flush line
-Clean coil
Pump Motor Not Running
-Pump motor switch off
-GFCI tripped
-No voltage to machine
-Clogged water nozzle
-Insufficient voltage/amperage
-Turn on pump motor switch
-Reset and test GFCI
-Check power source
-Clean water
-Use proper drop cord
Pump Noisy
-Air in suction line
-Pump valves dirty
-Check valve springs worn
-Low pump oil
-Pump bearings are worn
-Incoming water too hot
-Check inlet water fittings
-Clean/replace pump valves
-Replace check valves
-Add 5EA 30wt. non-detergent
-Replace/ rebuild pump
Reduce temperature/ ambient
Water in Oil
-High humidity environment
-Oil seal worn
-Plunger packing worn
-Change oil frequently
-Check and replace oil seal
-Check and replace packing
Water Dripping/Pump
-Plunger packing is worn
-Plunger retainer oil ring worn
-Cracked ceramics
-Install new packing kit
-Replace oil rings
-Replace ceramics
Oil Dripping
-Oil seal worn
-Cracked manifold
-Check and replace oil seals
-Replace manifold
Fluctuating Pressure -Unloader not adjusted
-Valves worn
-Dirt or blockage in valve
-Pump sucking air
-Worn plunger packing
-Adjust to specifications
-Replace with valve kit
-Clean or replace valve
-Check water/detergent supply
-Replace packing kit
Pump Head Overheating -Extended period in bypass -Pull trigger gun for water flow

Most Common Reasons for Experiencing Low Pressure and Troubleshooting Problems

Below we will be discussing several causes of low pressure most commonly appearing in conjunction with 3 other symptoms, pulsating, unsteady pressure, and steady, low pressure. We will start with the most common elements that fail and then lead into what components are difficult or easiest to check out.
Below we are referring to a cold-water pressure washer that is either tank fed or garden hose fed.

Pulsating Low Pressure - This can be felt as shaking or hard vibrating (also referred to as cavitations) when holding the spray gun while running the unit. Pulsating is usually associated with pump malfunction. It occurs when a cylinder misfires and results in a brief decrease in pressure.


First, check to see if there is damage to the pump’s head. If there is no visible damage, proceed to the following steps.

  1. Check to see that there is not debris blocking the valve. Inspect valves for deterioration.
  2. Check packings or seals for excessive wear.
  3. Check to ensure that piston or piston seals are not damaged. Leaking water from the crank case could easily indicated a damaged seal or valve.

* Note we skipped the rest of the machine and go straight to the pump in this case since this symptom is associated directly with the pumps pistons (plungers).

Unsteady Low Pressure - This is indicated by lower than normal pressure. The pressure may vary from slow to fast. Unsteady, Low Pressure usually signifies a problem with the water intake system (if the unit is tank fed.) This occurs when air enters the intake line.


First, check to see if there is an air leak. To detect an air leak, check the following components:

  1. Pump Inlet in Float Tank- Make certain that there is enough water in the feed tank so that the pump inlet is well below the water level.
  2. Ensure that your chemical injector is completely closed to prevent air from entering the intake line.
  3. Inspect the hose barbs to ensure that they are not cracked or weak. You can do this by giving them a firm shake. A damaged barb will bend or break.
  4. Examine all suction lines for cuts, cracks, abrasions, or heat damage.

If you have completed these 4 steps and still have not located the problem, you will need to pressure feed the suction lines to check for leaks. First, disconnect the feed line from the water tank and connect it to a garden hose. You do not need to run the machine, as the hose pressure is enough to reveal the leaks.

* After you turn the hose on, if there is water leaking from the pump crankcase the packing seals may be worn and need to be replaced. Water leaking from fittings indicates cracks or damage and may need to be replaced.

Steady Low Pressure - This is demonstrated when a machine is operating at a constant lower pressure than normal. Some possible culprits are pump starvation, loose belt drives, a clogged injector, or a badly worn tip.


  1. Pump Starvation (Tank Feed)- Check to ensure that the suction screen is not clogged. Pay special attention to make sure your intake lines are not obstructed or kinked. Pump Starvation (Garden Hose Fed)- Be sure that the garden hose spigot is producing adequate GPM. A damaged or kinked garden hose can also cause pump starvation. Check inlet filter and remove any obstructions. Inlet pressure regulator can malfunction or may be set too low.
  2. Loose Belt Drives- Check belt tension for slippage. If belt tension is off it can lower the RPMs that the pump is turning resulting in a lower operating pressure.
  3. High Pressure- If any leaks are occurring in the high pressure portion of the machine, it will contribute to pressure loss
  4. Wash Tip- Inspect wash tip for wear and tear. They need to be replaced often and can significantly reduce pressure. In addition, make sure you are using the correct orifice sized nozzles for your machine.

Inspecting the pump and unloader - After all the above has been checked and the problem still remains; we will turn to the pump/unloader to try and track down a solution to our low-pressure problems.


Unloader – While using your machine make sure that your unloader is functioning properly. It should move up and down and bypass the flow of water as you use or do not use the trigger gun. Also there is a quick check you can do to make sure the unloader is not bypassing unnecessary water. While depressing the trigger gun give the bypass hose a squeeze a feel for any unwanted water flow. If there is any water flow this could point to a malfunctioning unloader. *Please make sure the unloader is fully open to allow full pressure and flow.

Pressure Pump – The best way to check your pump and unloader is by separating the two. Remove the unloader, plug the bypass lines, and then connect your pressure hose directly to the pump. It is imperative that your trigger gun is fully depressed at all times when running this way. You may unwilling damage your pump otherwise. (Also be sure a pressure gauge is always attached to regulate the pressure output) If you are operating at normal pressure, your problem lies in the unloader. If the pressure is irregular have the pump serviced and then tested again.

Once your pump is operating at normal pressure reattach the unloader and make sure it functions properly as well.

* If you have a built in unloader this test cannot be performed.

Rapid Wear Out of Pump Internals – If your packings, seals, or other components are wearing out at a rapid rate you may be running the machine in bypass mode too long; running the pump dry can easily cause this rapid deterioration as well. Another cause can be running hot water through the pump itself. The seals and other components are not typically equipped for this unless otherwise stated in the pump specifications.

This basic overview of low pressure situations in cold water machines should help you deal with troubleshooting and resolving your problems with your pressure washer in the future.

Before trying any of these techniques described, be sure you understand what you are doing. If not seek the advice and help of an expert. There is a possibility and danger of equipment damage, shock, electrocution, burns, explosions, or fatal wounds can occur to you or a bystander without proper safety precautions and knowledge of the equipment. This material has been prepared as a guideline to help determine problems you are responsible for knowing exactly what you are doing. We are not help liable or responsible for any injuries or damage to equipment that is endured when trying these techniques.