Pressure washer spray pulses or surges

Symptoms

• Spray surges strong then weak in a rhythm
• Pulsing gets worse the longer it runs
• You hear a chugging sound from the pump
• Pressure is fine at first then starts pulsing

Likely causes

• CommonAir trapped in the pump or hoseAir pockets cause uneven pressure until they're purged, especially right after connecting a new hose.
• CommonInsufficient water supplyA pump that can't get enough water at the inlet will surge as it alternates between pressurized and starved.
• CommonClogged inlet filter screenA partially blocked screen restricts flow enough to cause pulsing without stopping flow entirely.
• PossibleWorn pump valves or sealsDebris or wear on the pump's internal check valves causes uneven pressure delivery.
• PossibleKinked or too-long garden hoseReduces flow to the pump inlet, especially with narrow-diameter hoses over long runs.

What to do

1. Turn off the engine or unplug the unit, then disconnect the wand and squeeze the trigger to bleed trapped air from the system.
2. Check that the garden hose is fully uncoiled, not kinked, and is at least a standard 5/8-inch diameter for good flow.
3. Turn the spigot fully open; a partially open faucet is a common hidden cause of surging.
4. Remove and clean the inlet filter screen where the garden hose connects to the pump.
5. Shorten the garden hose run if possible, since long or narrow hoses restrict flow to the pump.
6. Restart and run for a minute with the trigger open to see if pulsing settles down once air is purged.
7. If pulsing continues with good water supply and a clean filter, the pump's internal valves may need inspection by a repair shop.

Tools and parts

• None required for basic checks

When to call a pro

Persistent pulsing with good water supply usually means internal pump wear; a small-engine or pressure washer repair shop can rebuild or replace the pump.

Safety