Pressure washer pressure strong but pulsates/surges

blockage in the wand nozzle jet

check the check valves normally located behind hex screw caps and check for obstruction while having them out turn water on to flush the head from any debris

If the pump is pulsating rapidly most likely valves are leaking or debris under valve keeping one or more from closing. If the pump pulsates slowly, comes up to pressure then low pressure then repeats, problem is pressure regulator /bypass. Or you could have a combination of both. Try lowering the pressure to lowest setting to see if slow pulsation stops. As parts age within pump and debris hinder operation you can no longer operate at full pressure. To make the pump last, use highest pressure as needed and everyday work using only 60 to 75 percent of capacity.

If you have not flushed all air out of hoses prior to starting motor this may be the first symptom. If the water pressure from the spigot is competing with the clothes washer, shower etc. there may not be enough pressure to supply the demand of your pressure washer. A gauge attached to the spigot can give you a gallons per minute reading or take a five gallon bucket and time how long it takes to fill the bucket. ie: if the bucket fills in 2 minutes you have 2.5 gallons per minute. You may need this much to get un-interupted pressure for a 2400- or 2500 unit. Most residential properties are pipe sized from 3/4" pipe at the water main spigot at the front of the house down to a 1/2" pipe size at the rear of the house to maintain pressure.

Possible that there is dirt accumulation on the pressure washer.
1.check if the lines are clogged?
2. Check the gun open and blow air.
3. check the power switch .
4. check line to motor and if safety/load switch is acting due to overload caused by accumulation of dirt.
So clean up and check again.

Usually when a pressure washer is pulsating, either one or more pistions are not pumping. Quite often one of the check vavles for a cylider has broken and will not seal, which means you'v just lost one cylinder, and now you're running on two (etc) If a pressure washer is allowed to idle too long, re-circulating the water, it will get hot, and then melt the plastic container on the check valves. Go to : www. pressure-washer-parts.com You can order parts, and manuals.

Could well be the main jet slightly blocked in the carburettor.

I have d'same problem before. replace the head component with the 3 little cylinders,springs etc.. its a 1 piece part.

The motor doesn't pulsate when you are spraying and pulsattes when not spraying is normal otherwise the pressure will just keep building and burn out the pump. However, if you are not using the sprayer right away then the unit should be shut off until your ready to start again.
I hope the answer is helpful, please rate if the answer has helped in any way. Good Luck and have a great weekend.