Builds up to much pressure in hose and stalls engine

Frank, either the unloader valve is out of adjustment(try loosening it off) or it is faulty and needs rebuilt or replaced as most people do.
Check the attached vids,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."

When water is running through system, the motor has to run to keep the pressure built up. So, if the water is leaking out, the motor think it needs to keep running to keep the pressure built up. The leak needs to be fixed to the motor will not run constantly.

This happens when air gets inside the hose. An air bubble of sorts is in the hose and will not build pressure until you blow the air out of the line. Start the pressure washer, turn on the water. pull the trigger on the gun. It will spitter and spatter and come to a trickle. release the trigger on the wand. Pull the trigger again and it will eventually work it self out.

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

When the gun trigger is pulled, the back-pressure holding back the engine is reduced and the engine accelerates.

Your engine is dying when it should accelerate.

Good news is you have spark and combustion and fuel and the engine runs.

1) Check the exhaust port for build-up of carbon or dirt >>> the hot exhaust gas has to fly out of the exhaust port and if the port is clogged, then the engine stalls

2) Check the amount of fuel getting through to the carburetor >>> pull off the rubber hose entering carburetor from the gas tank >>> does gas run out freely? If gas does not run freely, then take apart your gas filter located just below gas tank

3) Remove air filter and see if problem continues. A dirty air filter can cause engine to stall since combustion requires oxygen coming through the filter. Replace the air filter.

4) Mess with the choke lever and see if you can find a setting where the engine works >>> our old power washer would never run when lever was moved to full throttle >>> we just left the choke lever at half throttle and the engine was happy

5) If above fixes don't fix the problem >>> the final suspect seems to be the carburetor >>> try some gun-out >>> maybe a trip to small-engine repair shop is required.

Trying to start a pressure washer with water supply on and gun trigger off will be a difficult task. It could be comparred to trying to start a lawn mower with the mower in tall grass. Place the mower on the drive or walkway and pulling the rope to start the engine is much easier. It is easy to start your pressure washer with no water in the system however there is a remote possibility that you could overheat the seals if you take too long to turn on the water. It is a little more difficult to start the washer with water supply on and someone holding the trigger to wand open. This will prevents pressure from building and making engine hard to start. You will not damage your washer if you start it with water supply off if you flood the pump and pressure hose with water first . Here is the procedure I use if i am working alone. I trun on the water to pump and open trigger to gun to allow water to flow into pump and pressure hose. Turn off water (leaving the water supply on will make it a little harder to pull starter). Start engine while holding trigger to gun open. When engine starts release gun causing unloader to activate circulating water in pump. Now turn on water and you are ready to work. If your system is under warranty however, I would advise to use the starting procedure outlined by mfg (hold open trigger to gun however). To get the longest life from unit try using it at say 75% of capacity or lower if your can and use max pressure on the tuffest jobs. Leaving your washer at full pressure for all jobs is like driving your car at 100 mph everywhere your go. Good luck.

May be it's ice-clogged?

I have a similar problem and diagnosed it to be a problem with the gun. I spoke to a technician that services this pressure washer and he walked me through all the diagnostic steps. The pump is working because there is pressure being built up and the gun sort of works because you can get water out before the washer is started. The technician said that the mechanism inside the gun is either clogged or broken. I am going to Home Depot or Lowes to purchase a new gun and will try it tonight. Guns are only about $30-40. He said generic is fine as long as the thread matches and PSI is in range. Good luck!

It is probably air locked....Here's what you need to do. Connect the garden hose, and HP hose, but not the gun. Turn on the water, and let it run while you make sure that there are no high points in the garden hose that can trap air....Work the hose so that any air is displaced through the pressure washer. Continue in this manner through the HP hose. Shut off the water and connect the gun. Turn the hose back on, and operate the gun for several minutes, pulling the trigger and releasing. This alternately allows the water pressure to build up on house pressure and then to depressure, pulling residual air from the system. Release the trigger, and start the machine. Usually, this is enough to get full washing pressure. If it is very difficult to start, you can hold the trigger down on the gun and pull the start cord at the same time. Holding the trigger down acts as an unloader, making the starting easier.
Hope that this helps, --W/D-- please feel free to rate this solution! Thanx!

It sounds like an air lock. Try this: With the machine off, connect the hose to the washer and let it run for several minutes to get all of the air out of the hose, and to purge any air out of the pump. Shut off the water, and connect the high pressure hose, but not the gun. Let the water run for several minutes. stretch out the HP hose and make sure that the air is displaced. Shut off the water, connect the gun, and purge as before. Now crank it washer up. As quickly as safe to do so, open the trigger to keep water moving through the washer. It should come up on pressure very quickly. It is better during normal operation to keep water moving through the system. When I am through for a while, I shut down my washer, but leave the trigger depressed to allow the pump to stay full of water, and cool. This prevents further problems when I restart it.
Hope this was useful.

Regards --W/D--