Pressure Washing "Surging"

FyrFyter33

New member
When my washer is not engaged and flowing water and is just sitting on the trailer idling while I spray chemical its making a "surging" sound. Like it revs up and down and up and down, but when I flow water it's smooth and has plenty or pressure and GPM. I'm leaning towards the motor because it doesn't do it while flowing water and I would think if it was the pump it would do it all the time. I've never really worked on the internal parts of a pump myself, I've been in business 6 years and do normal maintenance my own but never replaced rings or plungers or anything.

Any ideas or got a number I can send a video of it doing it too?
 
Do you have any leaks at the pressure hose connections or through the gun? The unloader in that video is cycling due to a leak at the connection between the pump and pressure hose.
 
..like Russ said, but also.. there's an "outlet check valve" in the outlet of the unloader..
T
he o-ring is the first part to go.. and you'll see why when you look at what it does.
The pressure actuated unloaders trap pressure on the outlet side of the valve,
in order to keep the valve in bypass when the gun is closed..
When there's a leak, or that o-ring is worn, ..the unloader thinks the gun was opened.

Half of retired unloaders just needed an o-ring on the outlet check valve.
 
..like Russ said, but also.. there's an "outlet check valve" in the outlet of the unloader..
T
he o-ring is the first part to go.. and you'll see why when you look at what it does.
The pressure actuated unloaders trap pressure on the outlet side of the valve,
in order to keep the valve in bypass when the gun is closed..
When there's a leak, or that o-ring is worn, ..the unloader thinks the gun was opened.

Half of retired unloaders just needed an o-ring on the outlet check valve.

Jerry, do you have a picture of where this o-ring goes?

Is this a regular o-ring that we can buy locally or a special size?

Thanks.
 
Any leaks will cause that to happen. I had a small leak on the hose real and it made that noise.
 
Outlet Check VAlve of unloader

Here's an image of the outlet check valve with the o-ring..
-ring should be Viton, and is usually a size .205 or so
 

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It sounds like a water leak within the high pressure side. Could be something with the fuel or carb system of the engine but most of the time it's a leak in the water system. Do you have a HP gauge on the pressure side of the system you can monitor to see if you are loosing water pressure? If you have a leak in the high pressure side, Longer hose will lengthen the time between surges and a very short hose will shorten the time between surges.

Longer hose would be like adding an accumulator to the system which would allow more time between surges. If you don't have a HP gauge to view, Change the length of hose and see if the surging speeds up or slows down. If no change, It's most likely within the engines fuel system. If you do see a change, It's within the pump and hose system.

Mike
 
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