Has no pressure, builds up when not holding trigger on gun, but when i press trigger shoots of with pressure the nothing just water comes out.

This is normal. The high-pressure car washer has certain dangers. If the water column of his spray gun is aimed at people, it will stab people. If the switch is turned on and spray water, then the pressure of the spray gun head will be sprayed around, which will accidentally hurt people. people, so it's designed this way.

Pump not working. Replace pump.

Hello,
This part should be available from the manufacture, have you check their website. It is normal when you turn the water on for a small string of water to come out the gun when you press the trigger even when the engine is not running.
Thanks

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

Good news, your engine runs
But your pump may be bad

Here's how to test your pump
Check oil as outlined lower down
Disconnect the washer hose and gun
Connect water hose and turn on water and water should pass straight through the pump
Look for clogs in the hose-end where water hose connects to machine

Turn on machine and see if water shoots out pump
If water shoots out of pump, but no water shoots out of gun, then you may have a 'mud-dobber' wasp clog in your washer line or gun

Look for clogs in the end of each water connection.
Now connect washer hose without the gun, tun on the machine, and see if water shoots out of washer hose
Finally, the gun trigger mechanism may be bad
I don't know which gun you have ... but we replaced guns on our machine now-and-then ... google-search power washer guns for a replacement

Check your pump oil
Pump oil is SAE20 or SAE30 non-detergent motor oil
Pump should be no more than 1/2 full of oil
Use plastic hose to drain pump oil
Do not turn machine on its side or turn machine over or engine oil will run into carburetor

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.

drain your system of pressure. remove your air cap and nozzle from the gun. slowly increase fluid pressure till it comes out of gun. this will clean out debri from gun. reduce pressure so you don't wast anymore fluid.
clean nozzle properly / completely
clean aircap. properly / completely
inspect needle tip for abnormal wear.
if cleaned properly you will find your gun works much better.

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!

Dear allbusiness9,
This problem is most probably due to a faulty Spill Valve( also called Control Valve). When the gun is released the spill valve is compressed and it either closes a micro switch or just opens from the bottom and keeps the water circulating. All spill valves keep the water circulating from the bottom part. Now when the gun is pulled (opened)...the spill valve extends and closes the bottom part, and thus water goes out of the nozzel. When you work with no nozzel, there is enough water flow to close the bottom part of the spill valve. So when the nozzel is placed back there is no chance that the bottom part leaks water. When the gun is started with the nozzel....the bottom part of a FAULTY spill valve,..will colapse and pressure drops. So to fix the fault you must change the Spill Valve. In some occasions, I also found that suction valves give this problem. A faulty sucktion valve will colapse under high pressure, and lets water pass the other way round.
But in my opinion and experience, your problem is in the Spill Valve.
Regards,
Fulltech.