B & S pressure washer

[wkndfirewood]

Hello All recently squired a B & S 5 hp 3000psi pressure washer. I hope that I can explain this so that the more knowledgeable members understand. The engine starts and runs fine, however the problem is in the pump. The unit will run fine as long the pressure wand is flowing water, as soon as the pressure wand stops flowing water the pump will lockup the engine. I have been looking for some type of relief valve to reduce the pressure on the gas engine. I'm hoping that the more knowledgeable members can provide some insight into this problem.

 

[guido]

wkndfirewood,

A picture of the unloader valve would help. But it sounds like it is stuck or the o ring seals ar bad, and not
unloading. There are sealed valves as well as serviceable ones.

If you can take it apart you may be able to clean it and lube it up. You will see
then if the O rings are good or not. They seal the low and high side ports of the
valve,

Guido.

 

[T.R.K.]

What is happening is the unloader valve is sticking, or just plain stuck. If you bought it and it is almost new, take it back and get
warranty. My experience is that if you take it apart and get it working now, it will stick again the next time you want to use it.

How the unloader works is when you allow the spray wand valve to close, the pressure goes up in the pump and the unloader valve is supposed
to open and allow the water back into the low pressure side of the pump, so while the unloader is open the water just goes in a circle. This
is why the mfg says to not allow it to run in bypass more than 2 minutes or so. And this is also why some pumps have another safety valve
that opens and dumps the water on the ground if it gets too hot.

 

[cwtech]

Is this a new unit or a used one?

Others have described the function of an unloader.

Most pressure washers have the unloader built into the pump. ....If it is un-repairable, you can install a separate unloader outside the pump.

Most separate unloaders are adjustable to set the system pressure. ....The unloader is connected to the discharge port of the pump. ....The spray hose is connected to the unloader. ....The unloading port of the unloader is tee'd into the pump inlet.
Sample of a separate unloader

 

[wkndfirewood]

 

[guido]

wkndfirewood,

The top has the pressure adjustment. Bet you the hex nut at the bottom will take the valve cartridge out.
If not, count the turns to get the top off, then soak the inside to see if it gets unstuck. The unloader valve nay have a number on it.

Just a speck of rust will get it stuck,

Guido.