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Pressure Washer Troubleshooting Guide

For Do It Yourself Pressure Washer Repair

Pressure washers have a variety of uses and are found in homeowner garages, small repair shops as well as large production facilities, with many being used on a daily basis to keep work areas and vehicles clean, and to provide safety from falls and injuries often associated with dirty or greasy floors. Pressure washers do require routine maintenance, which is often overlooked, resulting in larger repairs. The list below provides common symptoms reported by pressure washer owners, as well as possible causes and corrective actions to get your pressure washer functioning properly.

Diagnosing a pressure washer symptom is difficult, as it can be caused by more than one problem in different areas of the pressure washer. Although some pressure washer repairs will require the assistance of a professional repair facility, many DIY or Do It Yourself Repairs can be completed merely with a thorough inspection of your pressure washer, as well as following the guide below, to help to determine if the repair is a quick-fix such as a clogged nozzle, a more extensive repair such as replacing the burner nozzle or electrodes, or if it's something much more in-depth that requires the assistance of a service center.

We have organized the guide below to start with the most common problems and the easiest repair solutions.

If the Gas Engine Won't Run...
Possible Causes Are:

  • Out of Gas - Fill Gasoline Tank with appropriate fuel
  • Engine ON/OFF Switch is in OFF Position - Place engine ON/OFF switch in ON Position
  • Battery is Dead - Charge or Replace the Battery
  • Gasoline / Fuel Filter is Clogged - Replace or clean filter; bleed injector pump on diesel engines
  • Fuel Valve Closed - Some pressure washers have a fuel valve installed in the tank. Opening the valve will allow fuel flow through the system.
  • Dirty Battery Contacts - Clean connections
  • Battery Cables are Damaged or Disconnected - Connect or replace damaged cables
  • Loose Spark Plug Wire - Reconnect
  • Engine Flooded or Starved - Refer to Operator's Manual for correct choke or throttle setting
  • Low Engine Oil Level - Replenish engine oil supply. Most gas engines have a low-level shutdown, which will not allow the engine to start until the oil is at an appropriate level
  • Key Switch, Solenoid or Starter on Engine is Defective - Repair or replace faulty component
  • Engine, Pump or Gearbox is Seized - Identify, replace or repair seized component

If the Electric Motor Won't Start...

  • No Electric Power - Check electric cord, plug, and breaker. Some pressure washers such as Hotsy, also have a GFCI on the plug with a reset switch that requires pushing as soon as the unit is plugged in, or the unit will not turn on.
  • Power Switch is Inoperative - Check power switch
  • Electric Motor or Wiring Failure - Replace or repair motor and/or wiring

Pressure Washer Runs But Won't Spray...

  • Trigger Gun is Released - Squeeze trigger on gun
  • Supply Water is Turned Off - Open water supply valve
  • Clogged Spray Tip Nozzle - Clean or replace pressure nozzle
  • Pump is Dry and Needs Primed - Consult Owner's Manual for correct priming technique. One solution is to crack open the fitting on the high pressure outlet of the pump until water flows out.
  • If Water Spray Doesn't Improve Within 10-15 Seconds After Above Remedies - Discontinue running pressure washer. Recommend contacting service center for further evaluation, as damage to the pump will occur if allowed to run without water flow.

Trigger Gun Leaks or Won't Shut Off...

  • Debris in Gun Valve Assembly - Replace trigger gun or clean valve assembly
  • Worn or Missing O-ring - If using Quick Connect fittings, check the quick coupler between the trigger gun and hose connection for worn or missing o-ring


Pressure Washer Runs But Produces Low Pressure at Spray Tip Nozzle...

  • Inadequate Water Supply - Check for leaking, damaged or kinked hoses. Check water supply faucet and make certain it is completely opened. Use a minimum of 3/4 inch water supply hose. Check for debris that can clog the garden hose inlet screen as well as the inlet screen located at the hose connection on the pressure washer.
  • Partially Clogged, Damaged or Missing Pressure Nozzle - Clean or replace spray tip nozzle
  • Inlet Chemical Injector Valve is Open - If the chemical injector valve is open and the end of the detergent pick up tube is not inserted in detergent, air can be drawn through the detergent line, resulting in low pressure. Ensure that the pick up tube is fully immersed in liquid, or close injector valve.
  • Leaking Discharge Hose or Quick Coupler - Replace high pressure hose, quick connect fittings, or o-rings in quick connect fittings
  • Worn or Wrong Size Nozzle - An incorrectly sized or worn high pressure nozzle can reduce pressure. Consult our Nozzle Size Selection Chart to determine the correct nozzle size for your pressure washer.
  • Dual Lance Wand Valve is Open - Dual lance wands must be closed with a high pressure nozzle installed correctly to produce high pressure
  • Belt Slippage - Tighten, or replace with correct belt (not required on direct-drive pressure washers)
  • Unloader Valve is Worn or Adjusted Incorrectly - Install pressure gauge on pump head to adjust pressure. Check valve seat on unloader. Replace unloader valve. NOTE: the unloader valve is often referred to as the pressure regulator.
  • Stuck Inlet or Discharge Valves in Pump Head - Clean or replace worn or damaged pump valves
  • Restricted Water Inlet or Air Entering Inlet - Check hoses and fittings for restrictions and air leaks
  • Leaking High-Pressure or Low-Pressure Seals in Pump Manifold - Replace seals or consult service center
  • Coil Obstruction on Hot Water Pressure Washers - Coil obstructions or scale deposits inside heating coil can reduce water flow and pressure. May require replacement of coil. Recommend consulting service center for further evaluation or repair.

Detergent Injector Will Not Draw Soap or Poor Cleaning Results...

  • Knob on Detergent Injector is Closed - Open knob by turning clockwise
  • Inadequate Detergent Supply - Check level of detergent in supply container. Be certain that the end of the pick up tube (with screen) is fully immersed and that the detergent strainer is not clogged.
  • Pressure Washer Not in Low Pressure Mode - Downstream detergent injectors are designed for use in low pressure applications. Install low pressure spray tip nozzle or open dual lance wand.
  • Detergent Screen or Hose Clogged - Clean screen or hose as needed. Recommend always starting with a clean detergent container
  • Detergent Injector Check Valve is Clogged - Clean check valve at detergent injector inlet
  • Improperly Mixed Detergent or Incorrect Dilution Ratio - Detergents are available in a variety of concentrations; some that require dilution. Improper concentrations or poorly mixed powdered detergents will result in negative cleaning effects.
  • Rinsing with Hot Water - A final rinse with cold water is recommended to reduce water spotting

Pressure Washer Won't Produce Hot Water...

  • Burner Switch is in OFF Position - Place burner switch in ON position
  • Diesel Fuel Level is Too Low - Refill burner fuel tank with #2 diesel, kerosene or other approved fuel
  • Trigger Gun Released - Squeeze trigger gun. Water must be spraying in order for burner to light.
  • Thermostat Set Too Low or Faulty Thermostat - Increase thermostat to desired temperature or replace thermostat
  • Blown Fuse - Many hot water pressure washers have a fuse in the control box. Replace fuse as needed.
  • Gas or Diesel Engine is Running Too Slow - We recommend always running pressure washer engines at full throttle. Move throttle level to full throttle position to correct.
  • Fuel Filter is Clogged - Clean or replace fuel filter
  • Spray Tip Nozzle Not Installed - Most hot water pressure washers will not allow the burner to ignite unless producing high pressure water. Installing a high pressure nozzle and pulling the trigger gun will allow the burner to ignite.
  • Faulty Pressure Switch, Flow Switch or Vacuum Switch - These three different switches all control the burner ignition. A pressure switch must sense high pressure through the system prior to burner ignition; vacuum switches and flow switches must sense water flow, but not necessarily at high pressure. If these switches are not operating properly, they can cause lack of hot water production by the pressure washer, as well as prohibiting the burner from shutting off after the trigger gun is released. Replace switch.

Burner Continues to Fire When Trigger Gun Released...

  • Faulty Pressure Switch, Flow Switch or Vacuum Switch - Replace Switch (See Above Descriptions)
  • Faulty Fuel Pump Solenoid - Replace fuel solenoid

Pressure Washer Produces Black or White Smoke...

Using Incorrect Fuel or Water in Fuel Tank - Drain fuel tank and replace with correct, non-contaminated fuel
Improper Air Adjustment - Adjust the air bands on the burner assembly for proper fuel-to-air ratio. WARNING: Recommend replacement of coil insulation prior to adjusting fuel-to-air ratio. Unspent fuel can saturate the insulation, causing a fire in the heating coil burn chamber when ignition occurs.
Low Fuel Pressure - Most hot water pressure washers require more than 140 PSI of fuel pressure for correct burner operation. Consult your pressure washer Owner's Manual and adjust the fuel pump pressure to manufacturer's specifications.
Soot Build Up on Coils - Clean coils with soot remover or consult local repair facility for service
Improper Burner Nozzle - Consult the Burner Section of your Owner's Manual for manufacturer requirements of burner nozzle. Replace as needed.
Improperly Aligned Electrodes - Electrodes offer the spark that ignites the diesel fuel being spraying into the burn chamber by the burner nozzle. Misaligned or worn electrodes will not produce the proper spark, resulting in unspent fuel being sprayed into the burn chamber. Consult your Owner's Manual for proper alignment specifications, or replace electrodes as needed.