Pressure Washer Won’t Start or Has No Pressure? Fixes for Gas and Electric

Pressure washers sit for months and then get asked to work hard, which is the perfect recipe for a no-start. The good news is that the causes are predictable. Gas models fail for small-engine reasons, electric ones for electrical reasons, and both share a handful of pump problems. Work through the section that matches your machine.

Gas pressure washer will not start

1. Connect the water and turn it on first. Starting dry damages the pump, and many washers are simply hard to pull with no water.
2. Squeeze the trigger for a few seconds. Pressure trapped in the pump makes the engine nearly impossible to pull over; releasing it is the single most common fix.
3. Check fuel. Fresh gasoline, fuel valve open, and the cap vent clear. Fuel more than a couple of months old is suspect; see how long gasoline lasts.
4. Check oil. Low-oil shutdown prevents starting on most engines. Check on level ground.
5. Choke and switch. Full choke for a cold engine, off for a warm one. Engine switch on.
6. Spark plug. Remove it. Wet means flooding or no spark; dry means no fuel. Test for spark against the engine, and fit a new plug if in doubt.
7. Air filter. Remove and inspect; a clogged or oil-soaked filter stops a start.
8. Carburetor. If there is spark and fuel in the tank but the engine will not fire, or only runs on choke, the main jet is gummed with varnish from stale fuel. Clean the bowl and jet with carburetor cleaner, or fit a replacement carburetor, and refill with fresh fuel.

This is the same sequence as for any small engine, covered in more depth in small engine won’t start.

Electric pressure washer will not start

1. GFCI plug. Most electric washers have a GFCI built into the plug. Press reset. If it trips repeatedly, moisture has got into the motor or switch; let it dry thoroughly before trying again.
2. Outlet and breaker. Try another outlet, and check the house breaker. Washers draw 13 to 15 amps and do not share a circuit well.
3. Extension cord. A long or thin cord drops voltage and the motor hums without starting, or trips its overload. Use a 12-gauge cord of 25 feet or less, or plug the washer in directly.
4. Thermal overload. After heavy use the motor’s thermal protector opens. Switch off and let it cool for 20 to 30 minutes.
5. Trigger and switch. Many washers only run while the trigger is squeezed (total-stop systems). Connect the water, switch on, then squeeze the trigger. If nothing happens, the microswitch at the trigger or the pressure switch in the pump may have failed.
6. Motor hums but does not turn. A seized pump from freezing or running dry, or a failed start capacitor. Both are repair-shop jobs on all but the cheapest machines.

Runs but low or no pressure

This applies to both types and is usually easier to fix than a no-start.

• Nozzle. A partly blocked nozzle gives a weak or uneven spray; a wrong nozzle (soap nozzle) gives low pressure by design. Clean the orifice with the pin tool supplied, from the back, and flush it.
• Water supply. The washer needs more water than it uses, typically a fully open tap through a 5/8-inch hose with no kinks. A restricted supply makes the pump cavitate and pulse.
• Inlet filter. The small screen where the garden hose connects clogs with grit. Remove and rinse it.
• Air in the pump. With the engine or motor off, turn on the water and squeeze the trigger until a steady stream comes out of the wand with no spitting, then start the machine.
• Hose. A kinked, crushed or leaking high-pressure hose, or a leaking wand connection, drops pressure. Check the O-rings at each coupling.
• Worn nozzle. Nozzle orifices wear larger with use, which drops pressure gradually. Replace the nozzle set.
• Unloader valve. Stuck or worn, it bypasses water back to the inlet instead of sending it to the wand. On many pumps it can be removed, cleaned and refitted with new O-rings.
• Pump valves or seals. Pulsing pressure or water leaking from the pump usually means worn check valves or seals. Axial pumps are often replaced as a unit; triplex pumps can be rebuilt.

Pulsing pressure

A spray that surges on and off points to air in the pump, a restricted water supply, a partly blocked nozzle or a failing unloader, in roughly that order of likelihood. Work through the no-pressure list above.

Preventing the next failure

• Stabilize or drain the fuel before storage, and run the carburetor dry.
• Use pump saver or pump antifreeze before winter, and never let the pump freeze with water inside.
• Never run the washer without water, and never leave it running with the trigger released for more than a minute or two; the water in the pump heats and damages the seals.
• Rinse the inlet filter and nozzles after each use.

The small engine maintenance schedule covers the engine routine, and our pressure washer buying guide explains the pump types if yours is beyond repair.

Frequently asked questions