Simpson Pressure Washer Owner's Guide: Features, Maintenance & Common Issues

Note: This is our own independent owner's guide for Simpson pressure washers—not the official manufacturer manual. Exact controls, specifications, safety procedures, and performance details vary by model and year. Your official Simpson manual is the authoritative source for your specific unit's features, safety instructions, and warranty terms.

How Simpson Pressure Washers Generally Work

A Simpson pressure washer is a motorized pump system that takes water from a source (garden hose, tank, or inlet) and forces it at high pressure through a nozzle to clean surfaces. The core components are the engine or motor, the pump, the high-pressure hose, the spray gun, and various nozzles. When you start the machine, the motor or engine drives the pump, which pressurizes the water. The pressure is measured in PSI (pounds per square inch); most Simpson units in the consumer range operate between 2,000 and 4,200 PSI, depending on the model.

The spray pattern and pressure are controlled by the nozzle you attach and the trigger gun you squeeze. Releasing the trigger stops the flow. This basic setup is consistent across Simpson's lineup, though fuel type (gas vs. electric), pressure rating, and flow rate (GPM—gallons per minute) vary significantly by model.

Common Features and Controls on Simpson Pressure Washers

Most Simpson pressure washers share a similar control layout and set of features, though exact placement and options depend on your model and year. Consult your official manual for your specific unit's exact panel layout and button functions.

On/Off Switch or Button
Typically located near the engine or motor housing. Electric models usually have a simple on/off toggle; gas models often have a switch plus a primer bulb or choke for cold starts.

Throttle Control
Gas-powered units often include an adjustable throttle (or idle control) to manage RPM and, consequently, pressure output. Electric models typically run at a fixed speed.

Spray Gun and Trigger
The spray gun is your main control. Squeezing the trigger opens a valve and releases pressurized water. Releasing it stops flow immediately. This is one of the most important safety features on any pressure washer.

Nozzles
Simpson pressure washers typically come with several interchangeable nozzles, each color-coded by spray angle. A 0° nozzle delivers a narrow, intense jet; a 25° or 40° nozzle spreads the pressure over a wider area for gentler cleaning. Higher-angle nozzles are safer for surfaces like siding or vehicles. Your manual will show which nozzles are recommended for different tasks.

Detergent Tank or Attachment Point
Many Simpson units allow you to connect a low-pressure detergent dispenser or tank. This lets you apply soap or cleaning solution at lower pressure before rinsing with high pressure. Check your manual for your model's detergent system specifics.

Pressure Adjustment Valve
Some models include a manual valve (or unloader valve) that lets you dial pressure up or down. Others have fixed pressure. Your manual will clarify what your model offers.

Routine Maintenance for Simpson Pressure Washers

Regular upkeep keeps your Simpson running safely and efficiently. These are general maintenance steps; your official manual will have model-specific details and intervals.

Before Each Use

• Inspect the hose for cracks, bulges, or leaks. A damaged hose can burst under pressure and cause injury.
• Check the nozzle for debris or clogs. A blocked nozzle can increase pressure in unpredictable ways.
• Make sure water source is connected and flowing if you're drawing from a hose. If you're using a tank, fill it to the proper level.
• For gas models, check fuel and oil levels.

After Each Use

• Release pressure by squeezing the trigger with no nozzle attached, or by using the pressure relief valve if your model has one.
• Drain water from the pump and hose by running the unit briefly with the nozzle off, or by disconnecting and draining hoses manually.
• Disconnect the hose and store it coiled (not kinked) in a cool place.
• Store the unit in a dry location, away from freezing temperatures if possible.

Seasonal or Periodic Maintenance

• Oil changes (gas models): Check your manual for the correct oil type and change interval, typically every 50–100 hours of use or once a year.
• Air filter (gas models): Clean or replace the air filter every 50–100 hours, or more often if operating in dusty conditions.
• Spark plug (gas models): Inspect annually; replace if worn or fouled.
• Pump oil: Some Simpson pumps require periodic oil top-ups. Consult your manual for your model's pump type and maintenance schedule.
• Winterization: In freezing climates, drain the pump, hose, and tank before winter storage to prevent ice damage. Your manual will provide specific winterization steps for your model.

Common Issues and General Troubleshooting

Pressure washers are relatively simple machines, but a few problems show up frequently. These steps address typical causes; if the issue persists or involves electrical or fuel systems, consult your manual or a professional.

Low or No Pressure

• Check the nozzle: a high-angle nozzle (40°) delivers less focused pressure than a 0° nozzle. Swap to a narrower nozzle if pressure seems weak.
• Inspect the inlet screen or filter (if your model has one) for debris. A clogged inlet reduces flow and pressure.
• Verify the water source is flowing at adequate rate. A kinked hose or a slow faucet starves the pump.
• On gas models, ensure the throttle is set to full speed.
• If you're using detergent, the unit may be in low-pressure soap mode. Switch to rinse or high-pressure mode.

Engine Starts but Stalls Quickly (Gas Models)

• Check fuel: old or contaminated fuel can cause this. Drain the tank and refill with fresh, clean fuel.
• Verify the choke is set correctly for warm or cold starts. Consult your manual for the correct choke sequence.
• Check the spark plug: a dirty or worn plug can cause ignition problems.
• Ensure the air filter is clean.

Water Leaks from the Hose or Connections

• Tighten the connection at the spray gun, pump, or inlet where the leak originates. Do not over-tighten—hand-tight plus a quarter turn is usually sufficient.
• Inspect the hose for cracks. If cracked, the hose must be replaced; it cannot be safely repaired.
• Check the O-ring or seal inside the connection. If the hose is properly tightened but still leaks, the seal may be worn. Your manual may explain how to replace it, or a professional repair may be needed.

Uneven or Erratic Spray Pattern

• Remove the nozzle and inspect the tip for damage or debris. A chipped nozzle produces an irregular spray. Replace it if damaged.
• Clean the nozzle by soaking it or using a small pin to clear any mineral deposits (especially if you've used it in hard-water areas).

Unit Won't Start (Electric Models)

• Verify the power outlet is working and the cord is undamaged.
• Check for a thermal overload reset button on the motor housing; press it if present.
• Ensure the on/off switch is fully in the "on" position.

Loss of Prime or Air in the Line (Pump Runs but No Water Comes Out)

• Disconnect the inlet hose and pour clean water directly into the inlet port or tank.
• Turn the unit on briefly (a few seconds) to expel air from the pump.
• Reconnect the hose and test.

When to Call a Professional

Some issues require professional repair or parts replacement:

• Internal pump damage (noise, vibration, or continued low pressure after troubleshooting)
• Fuel system problems beyond simple fuel replacement (injector clogs, carburetor damage)
• Electrical faults (shorted wires, motor failure, broken switches)
• Pressure relief or unloader valve malfunction
• Hose or connector replacement (if you're unsure about the correct part or connection type)

Your official Simpson manual will flag safety-critical procedures that should only be performed by a technician. Never attempt repairs involving fuel lines, electrical circuits, or pressurized components unless you have training and your manual explicitly allows it.

Your Official Manual vs. This Guide

This guide explains how Simpson pressure washers generally work and covers the common features, controls, and troubleshooting steps you're likely to encounter. However, it is not a substitute for your official Simpson manual. Your manufacturer's manual contains the exact specifications, safety warnings, step-by-step assembly and operation instructions, detailed maintenance schedules, parts diagrams, and warranty information specific to your model.

For accurate details about your unit's controls, pressure rating, recommended maintenance intervals, correct fuel or oil types, detergent compatibility, and any safety procedures, always consult your official manual first. If you don't have your printed manual, contact Simpson directly or check their website for a digital version of your specific model.