Pressure Washer Won't Start | Fix Guide

Pressure washers combine small engine challenges with pump-related issues. When your pressure washer won’t start, the diagnosis follows familiar patterns - fuel, spark and mechanical systems - with some unique considerations for this equipment type. This guide covers gas-powered pressure washers from Honda, Briggs and other common engines.

Table of Contents

• Quick Diagnostic Checklist
• Fuel System Problems
• Ignition System
• Pump-Related Issues
• Engine-Specific Problems
• Starting Procedure
• Winterization and Storage

Quick Diagnostic Checklist

Before deep troubleshooting, verify the basics:

Check	Status
Fresh fuel in tank?	☐
Oil level correct?	☐
Fuel valve ON?	☐
Choke set correctly?	☐
Water supply connected?	☐
Water flowing through system?	☐
Kill switch in RUN?	☐

Water Supply Requirement

Critical: Many pressure washers won’t start or will be damaged without water supply connected. The pump needs water for cooling and lubrication.

Before starting:

1. Connect garden hose to inlet
2. Turn on water
3. Squeeze trigger gun to purge air
4. Verify water flows from wand
5. Then attempt to start engine

[NEED REAL IMAGE: Pressure washer water connection]

Fuel System Problems

Old fuel causes 80%+ of pressure washer starting failures. These units often sit unused for months between uses.

Old or Stale Fuel

Gasoline degrades within 30-90 days, faster with ethanol content.

Symptoms:

• Cranks but won’t fire
• Starts briefly then dies
• Hard to start, runs rough

Solution:

1. Drain old fuel from tank
2. Drain carburetor bowl (small screw at bottom)
3. Add fresh fuel
4. Try starting
5. If still won’t start, carburetor cleaning needed

For fuel quality issues, see our small engine fuel problems guide.

Carburetor Issues

Varnish from old fuel clogs carburetor passages quickly. Pressure washers are especially prone because they sit unused.

Symptoms:

• Cranks but won’t fire
• Starts then dies immediately
• Runs only with choke on
• Surges at idle

Quick test: Remove air filter, spray starting fluid into carburetor intake.

• Fires briefly = Carburetor problem confirmed
• Nothing = Spark or compression issue

Solutions:

1. Remove and clean carburetor
2. Replace gaskets and diaphragms
3. Clear all jets and passages
4. Or replace with new carburetor ($20-40)

See our how to clean a carburetor guide for detailed instructions.

Fuel Filter and Lines

Symptoms:

• Fuel not reaching carburetor
• Engine starves under load
• Slow priming

Check:

• Inline fuel filter (replace if discolored)
• Fuel lines (replace if cracked or hard)
• Fuel valve operation

[NEED REAL IMAGE: Pressure washer carburetor]

Low Oil Shutoff

Many pressure washer engines have low oil shutoffs that prevent starting.

Symptoms:

• Engine cranks but won’t fire
• No spark (oil sensor grounds ignition)

Check: Oil level on dipstick. Add oil if low. Some sensors fail and give false readings - engine may need tilted to reset sensor.

Ignition System

If fuel delivery is confirmed, check spark.

Spark Plug Testing

Procedure:

1. Remove spark plug
2. Reconnect plug wire
3. Ground plug body against engine block
4. Pull starter cord
5. Watch for spark at electrode

Results:

• Bright blue spark = Good ignition
• Weak yellow/orange spark = Replace plug
• No spark = Plug, coil or wiring issue

Spark Plug Specs

Engine	Plug	Gap
Honda GX	NGK BPR6ES	0.028-0.031”
Briggs	Champion RC12YC	0.030”
Kohler	NGK BPR4ES	0.030”

Replace spark plug annually or if fouled/worn.

Ignition Coil

No spark with a new plug suggests coil failure.

Testing:

1. Disconnect kill switch wire
2. Retest for spark
3. Spark now = Kill switch/wiring problem
4. No spark = Coil failure

Air gap: 0.010-0.014” between coil and flywheel.

Kill Switch Problems

Corroded or shorted kill switches ground the ignition.

Test: Disconnect kill switch wire from coil and test for spark. If spark returns, switch or wiring is the problem.

Pump-Related Issues

Pressure washer pumps create unique starting challenges not found on other small engine equipment.

Locked Pump

Water left in the pump can freeze in winter or cause mineral buildup.

Symptoms:

• Pull cord extremely hard to pull
• Engine won’t turn over
• Grinding feeling when pulling

Solutions:

1. If frozen, bring to warm location and let thaw
2. Try pulling cord in short bursts
3. Disconnect pump from engine if possible
4. Address pump separately

Prevention: Always run pump protector/antifreeze before winter storage.

Pump Vapor Lock

Hot pump transfers heat to carburetor, vaporizing fuel.

Symptoms:

• Won’t restart when hot
• Starts fine when cold

Solution: Let cool 15-30 minutes, then restart.

Thermal Relief Valve

Running the pump without pulling the trigger causes overheating. Some units have thermal protection.

Symptoms:

• Engine shuts off after running at idle
• Won’t restart immediately

Solution:

• Let cool
• Ensure water flows when running
• Never let pump idle more than 2-3 minutes without pulling trigger

[NEED REAL IMAGE: Pressure washer pump]

Pump Seizure

Severe mineral buildup or freeze damage can seize the pump.

Symptoms:

• Pull cord locked or very hard
• Engine turns if pump disconnected

Solution: Pump rebuild or replacement usually required.

Engine-Specific Problems

Honda GX Engines

Common on quality pressure washers.

Specific issues:

• Auto-choke (GCV) can stick
• Oil Alert sensor may give false readings
• Carburetor responds well to cleaning

See our Honda GX160/GX200 carburetor guide.

Briggs & Stratton Engines

Very common on residential pressure washers.

Specific issues:

• Plastic carburetor components
• Primer system failures
• Low oil sensor

See our Briggs & Stratton engine problems guide.

Kohler Engines

Found on some commercial units.

Specific issues:

• Electric fuel solenoid
• Fuel pump (if equipped)

See our Kohler engine problems guide.

Starting Procedure

Correct procedure prevents many problems.

Cold Start

1. Connect water supply hose
2. Turn water on at spigot
3. Squeeze trigger gun to purge air
4. Verify water flows from wand
5. Release trigger
6. Set choke to FULL (closed)
7. Turn fuel valve ON
8. Set throttle to FAST (if adjustable)
9. Pull starter cord until engine fires
10. Move choke to HALF
11. Pull until runs smoothly
12. Move choke to OFF

Warm Start

1. Verify water connected and flowing
2. Choke OFF
3. Pull starter - should start in 1-2 pulls

After Use

1. Release trigger, let idle briefly
2. Turn off engine
3. Turn off water supply
4. Squeeze trigger to release pressure
5. Disconnect hoses

Winterization and Storage

Proper storage prevents most starting problems.

Before Storage

Fuel system:

1. Add fuel stabilizer to tank
2. Run engine 5 minutes to circulate
3. Or drain fuel completely and run until carb is empty

Pump:

1. Disconnect hoses
2. Connect pump saver/antifreeze
3. Pull trigger to draw solution through pump
4. Pump several times until solution exits wand

General:

1. Clean entire unit
2. Store in dry location
3. Cover to prevent dust
4. Store upright

For more storage tips, see our small engine storage guide.

Spring Startup

After storage:

1. Check oil level
2. Add fresh fuel
3. Connect water
4. Follow cold start procedure
5. If won’t start, carburetor likely needs cleaning

When to Get Professional Help

DIY-Friendly

• Spark plug replacement
• Air filter service
• Carburetor cleaning
• Fuel system service
• Basic pump maintenance

Professional Service

• Pump rebuild or replacement
• Internal engine repairs
• Unloader valve issues
• Pressure regulation problems

Related Guides

• How to Clean a Carburetor
• Small Engine Fuel Problems
• Small Engine Storage
• Honda GX160/GX200 Carburetor
• Briggs & Stratton Engine Problems
• Generator Won’t Start

Summary

Pressure washer starting problems usually trace back to old fuel and carburetor issues. These units sit unused for long periods, allowing fuel to degrade. Always connect water before starting - the pump needs it. If the engine cranks but won’t fire, clean the carburetor. If the pull cord is extremely hard, the pump may be frozen or seized. Proper winterization with fuel stabilizer and pump protector prevents most spring startup problems.