Pressure Washer Won't Start? What to Check

Part of our complete Small Engine Troubleshooting Guide.

Work through it in this order. The first two steps cost nothing and account for most of the machines that reach us as a no-start. The later ones are the jobs worth paying someone to do properly rather than guessing at on a wet driveway.

1. Check the Pump Before You Blame the Engine

On most homeowner machines the pump is bolted straight onto the end of the engine crankshaft, so the two turn together. That means a pump holding trapped pressure, or one that has seized, makes the recoil cord feel immovable — and it reads exactly like a locked-up engine. Plenty of machines arrive here written off for that reason alone.

Connect the garden hose, turn the water fully on and squeeze the trigger for a few seconds to purge the air and drop the pressure, then try the cord again. If it pulls freely now, nothing was ever wrong with the engine. If it still will not move, stop pulling: a pump that sat through a freeze with water in it is a bench job, not a driveway one.

2. The Controls That Stop a Healthy Engine

Then work along the top of the machine. The fuel valve has to be open, the engine switch has to be on, and a cold engine needs the choke closed and the throttle up. Any one of them left where it was at the end of last season gives you a machine that cranks and never fires.

Two more worth knowing. Many units carry a low-oil shutdown that is wired into the ignition, so a level that has dropped over a long summer stops it starting rather than warning you first — check the oil on level ground before anything else. And the water has to be on: running one dry damages the pump, and some machines will not build at all without a full supply.

3. Last Season's Fuel Is the Usual Culprit

If it turns over properly and still will not fire, suspect the fuel first. Ethanol-blended pump gasoline does not keep. Left in a tank through a damp Kentucky summer it draws in water, loses the light fractions a cold engine needs to light, and leaves varnish behind in passages barely wider than a pin.

Drain it and refill with fresh fuel rather than topping up over the top of the old. If it fires on full choke and dies the moment you open it, that is the signature of a partly blocked jet rather than a tired engine — our guide to ethanol gas and small engines covers why it turns bad so fast.

4. Follow the Fuel From the Tank Forward

Fresh fuel in the tank is not the same as fuel reaching the cylinder. Follow it forward before anyone takes a carburetor apart:

• The tank and its screen. Look for water sitting under the fuel and for the fine mesh in the tank outlet, which catches the sediment stale fuel drops.
• The in-line filter. Cheap, often forgotten, and the first thing to clog. Note which way the arrow points before you fit a new one.
• The choke and throttle linkage. A plate that is not closing fully, or a stiff cable, means a cold engine never gets the rich mixture it needs to light.
• The carburetor bowl. If everything upstream is good and it still will not run, the varnish is inside — see our guide to small engine carburetor cleaning.

5. Spark, the Plug Cap and Flooding

Pull the plug and read it. Dry and sooty black says it has been running rich or the plug is finished; wet with fuel says flooded; pale, dry and odourless says it is getting no fuel at all, which sends you back to the step above. Check the gap against the manual and fit a new plug rather than cleaning one that has done a couple of seasons.

Then look at what feeds it. A plug cap goes loose or corrodes inside after a few years of being pulled on and off, and the lead can break where it enters the cap while the outside looks perfect. Repeated pulls with the choke shut flood the cylinder, so once a plug comes out wet, dry it, open the choke fully and pull with the throttle held open to clear the excess.

6. When It Belongs on a Bench

Four faults are worth stopping for. A machine that pulls over fast and light with no resistance has lost compression, and no amount of fuel or spark will change that. One that will only start hot, or that kicks back against the cord, often has valve clearance that has closed up with wear — our guide to valve lash adjustment covers what that involves.

The third is the recoil starter itself, which takes more abuse on this machine than on any other because of the pressure in the pump. The fourth is the pump: oil that has gone milky means water has got past a seal, and a unit that starts and runs but will not build pressure is a water-supply, nozzle or unloader question rather than an engine one — our pressure washer maintenance and repair guide works through that side of it.

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Matching the Symptom to the Cause

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When to Call the Shop

Purging the pump, opening the fuel valve, draining stale gas, fitting a new in-line filter and a new plug are all driveway jobs, and between them they wake up most machines that have simply sat. If one of them fixes it, note which one, because a machine put away the same way next autumn will do the same thing again — and the first hard freeze is what turns a damp pump into a replacement.

Bring it to us when the cord still will not move after the pressure is off, when fresh fuel and a clean filter change nothing, when the carburetor needs stripping rather than a squirt of cleaner, or when compression, valve clearance or the pump itself needs measuring. We will tell you what it needs and what it is not worth spending on, and give you a firm quote before any work begins.

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Pressure Washer No-Start FAQ

Why won't my pressure washer start after sitting all summer?
Usually the fuel, and sometimes the pump. Gasoline left in the tank for months takes on water and leaves varnish in the carburetor, and a pump stored wet can seize. Drain the old fuel, refill with fresh, and check that the cord still pulls freely.

The pull cord will hardly move. Is the engine seized?
Not necessarily. On a direct-drive machine the pump is bolted to the crankshaft, so trapped pressure or a seized pump feels exactly like a locked engine. Connect the hose, turn the water on and squeeze the trigger, then try again.

Should I use starting fluid on a pressure washer?
We would leave it alone. It tells you very little that reading the spark plug does not, and it washes the oil film off the cylinder wall while it is at it. Find out whether you have fuel and spark instead, in that order.

Do you repair pressure washers in Richmond, KY?
We do, across Madison County. Carburetor cleaning and rebuilds, fuel valves and filters, recoil starters, pumps and unloader valves, valve clearance and compression testing, with pickup and delivery available and a firm quote before any work begins: (859) 661-8877.