Engine runs great but the pump wont put out high pressure spay

blockage in the wand nozzle jet

Check for air leaks above the top of the feeder tube. If it leaks air there, then no suction. Bad gaskets often cause this.

Im currious what on a pressure washer required "cleaning" what were you running thru it other than water ?

do you think you might have dissasembled something on engine part and might not have assembled it back quite right?

Try reduce the pressure or change the spray tip seal areyouusingthe correct size tip for the paintyou are sprsying

Disconnect hoses.
Look for kink in water hose.
Check incoming water connection for filter washer
Replace filter washer
If you don't have a filter washer, put one in.
Hook up water, and turn on
Water should come out other side of pump.
Turn on machine.
Do you get pressured water out of pump.
If no pressure, then pump is suspect
Hook up washer hose without gun
Does pressure come out of washer hose
Finally, the gun trigger may be bad.

We had to buy guns now and then.
Search for pressure washer guns
Following link shows guns we used:
http://www.ultimatewasher.com/pressure-washer-trigger-guns.htm

Take hose and gun off pump.
Start engine.
See if pressure comes out of pump.
Next, remove water hose and look at filter washer.
Clean or replace filter washer.
Turn on water and it should come out of pump on other side.
These steps will tell you if problem is water supply or pump.

Sometimes the problems happen because the gun lever is bad.
Hook up hose but not the gun
See if pressure comes out hous.
These steps will tell you if problem is gun or hose.

that is sure signal of insufficient water supply!

try easy solution first:
make sure that your mains is fully open, that tap on whihc hose is hook up is fully open and hose is of "decent" diameter to allow sufficient flow.

if above solution do not work then you need to make another, more difficult arrangement:
prepare 20litres pressure tank with inlet connected to mains and outlet by short hose to power washer, fill it with water from mains, keep it under mains pressure and use karcher power washer normaly. this will solve water supply problem. twenty litres will last about 2min, because it is re-filled, under standard pressure therefore it will last about 3min...

third possibility is to stop washing...

if you find my advice helpfull, please do not hesitate to left the comment and vote for me, thanx!

The reason it stops spraying might be a clogged gun, hose or nozzle-tip.
The reason for pressure buildup killing the engine might be a stuck unloader valve in the pump.

While you are checking each component of the "output" side, spray some penetrating lube into the "input" side of the pump (where the garden hose connects) and let it be working on the unloader valve.

Fix the spraying problem first:
Start at the nozzle and verify that it is open by using low-pressure air. Clean or replace as needed. Next check the hose (with nozzle and gun unhooked) and finally the gun/trigger mechanism.
All must be clear and open to perform correctly.

Next, pour a few ounces of power steering fluid (or similarly LIGHT oil) into the garden hose, attach it to the pump and turn on the water supply.

Leave the "output" hose, gun, etc. UNHOOKED and point the output port of the pump (where the high-pressure hose connects) towards a vacant, safe area.
Startup the engine and allow the oil in the garden hose to work its way thru. (About 1 -3 minutes of run-time.) Shut it down and attach the high-pressure hose.
Hope this solves the problem!

THERE SHOULD BE A PRESSURE REGULATOR ON THE PUMP YOU CAN ADJUST FOR MORE PRESSURE THIS COULD BE THE PROBLEM. ONCE YOU PRIME THE UNIT THE REGULATOR SETS ITSELF AND WHEN YOU PULL THE TRIGGER AGAIN THE SEAT AND SPRING MAY BE STAYING OPEN AND NOT LETTING THE UNIT BUILD PRESSURE

Dear davedulmage,
To see if the unit is OK....first you must switch it on without water and without high pressure hose and gun. If machinr works smoothly, try by attaching a water supply. Now run the pump with water coming out of the outlet. If also in this case all runs smooth, then attach high pressre hose with gun but without lance. Put on the machine with gun open(to reduce initial resistance) and when you see a clear flow of water coming out...close the gun. The machine should stop. In this case I am suspecting that when you open again the gun the machine will not work. So it seems that when pressure is built in the pump a fault is occuring in the Spill Valve or also called Control Valve. When the gun is closed and pressure built up, this spill valve contracts and switches the pump off. When the gun is opened, the spill valve extends, putting the machine on and closing a valve at the base of the spill valve. So in your case it seems that the spill valve needs to be renewed. A spill valve gets stuck by incorrect using of the pump. For example leaving the pump with pressure in it for a long time. Also it gets stuck by detergents and chemicals. Sometimes I lubricate Spill Valves with high quality silicon grease....but it is much more practical to change it. When a new spill valve is put in....always run the pump with no load. This by usiing the gun without lance or wands, resulting in low pressure. If all OK...add a lance or wand that you are sure it is good. One final thing....to get to this spill valve you must put apart the body and expose the pump. If you are not that good at doing this job...it is better done by a more knowledgeable person. But changing the spill valve is worth it....because it is cheaper than a new machine.
Regards,
Fulltech.