Pressure Washer — Won't Start

Before you begin

Never point the spray gun at yourself or others, even during troubleshooting with the engine off. Disconnect the spark plug wire before any work near the pump or engine. If the unit has sat with water in the pump over freezing temperatures, check for cracked pump components before running it.

Spark plug test — safety first

Remove the spark plug, reconnect it, and ground the metal body against the engine block — away from the plug hole and any spilled fuel. Easiest to see in a dim area.

Trigger not squeezed during start

With the trigger released, the pump is a closed system and builds pressure immediately, which some engines can't overcome to start, or which trips a cutoff switch designed to protect the pump.

1. Squeeze and hold the trigger while pulling the starter cord or engaging electric start.
2. Once running, you can release the trigger briefly, but expect the engine behavior described elsewhere in this guide if it dies when you do — that's a separate, related system worth checking if it happens.

Empty tank or stale fuel

Pressure washers are classic seasonal-use equipment — often run once or twice and then stored for months, which makes stale fuel one of the most common reasons one won't start when you finally need it.

1. If empty, fill with fresh gasoline per your manual's spec.
2. If fuel has been sitting, drain it fully into an approved container and refill with fresh gas.
3. If it still won't start after fresh fuel, the carburetor bowl and jets have likely gummed and need cleaning — expect this after several months of storage with fuel left in.
4. Going forward, add a fuel stabilizer before storage, or run the tank dry before putting it away.

Parts that may help: e.g. Sta-Bil, Sea Foam, carburetor/choke cleaner spray

Low oil shutoff

Many pressure washer engines have a low-oil sensor that prevents starting entirely, protecting the engine — commonly mistaken for a mechanical fault.

1. Add oil to the full mark using the weight in your manual (commonly SAE 30 or 10W-30).
2. Check on level ground for an accurate reading.
3. If oil was very low, check for a leak before running under load again.

Parts that may help: SAE 30 / 10W-30 small engine oil, small funnel

Cold-start procedure not followed

Like most small engines, pressure washers need extra fuel enrichment to start cold.

1. Set the choke to full/closed for a cold start, then gradually move to run as it warms up.
2. Remember to also keep the trigger squeezed during this process, per the earlier check.

Faulty pressure cutoff switch (TEC system), not the ignition coil

Since spark returned once that wire was isolated, the coil is fine — the pressure-sensitive cutoff switch (or its wiring) is incorrectly signaling high pressure and blocking ignition, even with the trigger squeezed and pressure relieved.

1. Check the unloader valve on the pump — this is what the cutoff switch monitors, and a stuck or misadjusted unloader can create a false 'high pressure' signal even with the trigger open.
2. Inspect the switch's wiring for corrosion or a loose connector.
3. Replace the switch if the unloader and wiring both check out — it's a relatively low-cost part.
4. Reconnect the wire once repaired — it protects the pump from being run against a closed system, which is a real failure mode if bypassed permanently.

Parts that may help: replacement pressure cutoff (TEC) switch, pump unloader valve

Faulty ignition coil

Since spark still didn't return with the cutoff circuit isolated, the coil itself is the likely failure point.

1. Clean the flywheel magnets and coil laminations with fine sandpaper if accessible.
2. Check the coil's air gap against your engine's spec with a feeler gauge if adjustable.
3. If that doesn't restore spark, replace the ignition coil.

Parts that may help: engine-model-specific ignition coil, feeler gauge set for coil air gap / valve clearance

No spark — plug or ignition system

Without isolating the cutoff circuit, replacing the plug first is the cheapest and most common fix before assuming a deeper ignition fault.

1. Replace the spark plug with the correct type/gap for your model.
2. If a new plug still gives no spark, the ignition coil or the pressure cutoff switch wiring described above likely needs testing — worth revisiting the isolation test if you become comfortable with it.

Parts that may help: engine-specific spark plug

Fouled spark plug

A wet or oily plug points to flooding; a carbon-caked plug points to a rich mixture or dirty air filter.

1. Wipe clean or replace the plug — replacement is more reliable.
2. If wet with fuel, let it sit open 10-15 minutes before retrying.
3. Check the air filter next, since a dirty filter is a common contributor.

Parts that may help: engine-specific spark plug

Clogged air filter

A blocked filter starves the engine of air, common on units stored in a garage or shed between seasonal uses.

1. Clean or replace per your model's filter type.
2. Check at the start of each season, even if barely used.

Parts that may help: engine-model-specific air filter

Damaged carburetor float or needle valve

A stuck or waterlogged float prevents the bowl from filling correctly — very common after long storage periods, which is typical for seasonally-used pressure washers.

1. Replace the float and needle valve as a set — sold together in most carb rebuild kits.
2. Clean all jets and passages with carb cleaner spray while the bowl is off.
3. Check the float sits level per your manual's spec before closing the bowl back up.

Parts that may help: engine-model-specific carburetor rebuild kit

Low compression — valve, ring, or head gasket issue

With fuel, spark, and carburetor all ruled out, low compression points to something inside the engine — a valve not seating, worn piston rings, or a blown head gasket.

1. A valve clearance check (feeler gauge against your engine's spec) is the least invasive thing to rule out first.
2. Rings and head gaskets require full disassembly — worth weighing repair cost against the unit's value before taking this on yourself.
3. This is a good candidate for a local small engine shop if you'd rather not go further.

Parts that may help: small engine compression tester, feeler gauge set for coil air gap / valve clearance

If this doesn't resolve it, this is a good candidate for a local small engine shop rather than continued DIY diagnosis.

Needs professional diagnosis

You've ruled out trigger position, fuel, oil, choke, spark, air filter, carburetor internals, and (if tested) compression. Remaining causes need equipment or experience beyond typical home DIY.

1. This is a good candidate for a local small engine shop — bring your notes on what's already been ruled out.

If this doesn't resolve it, this is a good candidate for a local small engine shop rather than continued DIY diagnosis.