Where is the spill valve on my 3.550 pressure washer

spill valve is probably the valve that releases excess pressure or heat caused by not using trigger while machine is running. allowing the water the escape onto the floor

The power washer stops when the gun is closed. This happens because pressure is exerted on a control valve (Spill Valve)...which in turn touches a micro switch and cuts electricity. Now most probably your machine is kickin in an out because the spill valve got faulty This happens when one stores away the machine with pressure still in it. NEVER store a power washer with pressure in it. The spill valve also gets faulty because left with soap and machine not rinsed. I rarely service spill valves...I change with a new one.
To locate the spill valve open cover (using a TORX T15screw driver)...and where you see 2 wires coming out...there is the spill valve.
Sometimes these machines have the spill valve incoporated with the head....in that case the whole head must be renewed. I also wish to tell you to try using the machine with out the lance. If all works good...then the on and off could also be comming from a faulty nozzel.
Regarding the Spill Valve...when it gets faulty...the machine also lose pressure. So in your case it is most likely that the spill valve is faulty.
Regards,
Fulltech.

Dear Sir,
The power washer stops when the gun is closed. This happens because pressure is exerted on a control valve (Spill Valve)...which in turn touches a micro switch and cuts electricity. Now most probably your machine is dead because the spill valve is stuck down and closing the micro switch. This happens when one stores away the machine with pressure still in it. NEVER store a power washer with pressure in it. The spill valve also gets gammed because left with soap and machine not rinsed. I rarely service spill valves...I change with a new one.
To locate the spill valve open cover (using a TORX T15screw driver)...and where you see 2 wires coming out...there is the spill valve. If you can manage to do this..you can try if you want to lubricate it by spraying SILICON spray. If you get it out..you use silicon grease.
Sometimes these machines have the spill valve incoporated with the head....in that case the whole head must be renewed.
Regards,
Fulltech.

Dear Sir,
The power washer stops when the gun is closed. This happens because pressure is exerted on a control valve (Spill Valve)...which in turn touches a micro switch and cuts electricity. Now most probably your machine is cutting out because the spill valve is getting faulty or stuck down and closing the micro switch. This happens when one stores away the machine with pressure still in it. NEVER store a power washer with pressure in it. The spill valve also gets gammed and faulty because left with soap and machine not rinsed. I rarely service spill valves...I change with a new one.
To locate the spill valve open cover (using a TORX T15screw driver)...and where you see 2 wires coming out...there is the spill valve. If you can manage to do this..you can try if you want to lubricate it by spraying SILICON spray. If you get it out..you use silicon grease.
Sometimes these machines have the spill valve incoporated with the head....in that case the whole head must be renewed. I wish to tell you to try using the machine without the lance. If it works correctly, then you have a faulty nozzel in the top of the lance. IMPORTANT...never run a power washer with water being fed!!!!
Regards,
Fulltech.

Dear Sir,
The power washer stops when the gun is closed. This happens because pressure is exerted on a control valve (Spill Valve)...which in turn touches a micro switch and cuts electricity. Now most probably your machine is dead because the spill valve is stuck down and closing the micro switch. This happens when one stores away the machine with pressure still in it. NEVER store a power washer with pressure in it. The spill valve also gets gammed because left with soap and machine not rinsed. I rarely service spill valves...I change with a new one.
To locate the spill valve open cover (using a TORX T15screw driver)...and where you see 2 wires coming out...there is the spill valve. If you can manage to do this..you can try if you want to lubricate it by spraying SILICON spray. If you get it out..you use silicon grease.
Sometimes these machines have the spill valve incoporated with the head....in that case the whole head must be renewed. The lack of pressure is sometimes also due to a faulty spill valve. So if this valve is corrected or changed the pressure returns. Weak pressure also is caused by faulty suction and delivery valves (6 in all). Remove the gun from machine...connect water...and start. Touch the outlet...if you feel suction ...the valves are faulty. Then for a few seconds try to test the inlet. Do this fast so that you do not turn the machine for long without water. If from the inlet you feel pushing....the valves are faulty. Which ever case always change the 6 valves.
Regards,
Fulltech.

If the spill valve activates is "spills" water under the washer. There is a restriction or the pump has become inefficient and will not pump the volume and pressure it should at full RPM.

Dear loliver2,
When trigger is shut, pressure builds up in machine and this activates a control-valve or often called a Spill Valve. This Spill Valve compresses with the built up pressure and switches off a micro-switch...which in turn stops the machine. Now when this Spill Valve gets faulty, it starts compressing and de-compressing undr pressure. Thus the micro switch is activated on and off. That is why your machine is starting and stopping. Now this Spill Valve also controls pressure. So to fix the fault you must change the Spill Valve with a new one. Myself I rarely service Spill Valves. You can locate the spill valve after you open the cover. The spill valve is usually covered with a plastic cap that contains the electrical micro switch. I do not know what model you have....but sometimes to improve the pressure you must also change the suction and delivery valves. But in most cases like yours...it is only the Spill Valve that is causing the starting and stopping and the low pressure.
Regards,
Fulltech.

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.

Dear Pgarciax,
It is important that you must have mentioned the model number of your Karcher. Just the same I can surely say that your machine's fault lies in the "SPILL VALVE"
When the gun is open and pressure is being produced, the spill valve is in a relaxed position. Also it has at the bottom a valve, which when pressure is produced it is closed. If this does not close due to dirt or corrosion, the pessure goes down. Now when you close the gun,pressure forces the spill valve down to close the electrical system. Now if the "o" rings of the spill valve are damaged, the machine will start going on and off while in stand-by. So if you know how to locate the Spill Valve, all one has to do is change it with a new one.
In some Karcher machines there are 2 spill valves. One regulates pressure and the other one is for switching off the machine when the gun is closed.
Low pressure could also be due to faulty suction or delivery valves. Most probably the suction valves.
But when saying that there are short interruptions while in stand by, I stick to the fact that the spill valve needs renewing.
Regards,
MG.

New spill valve!