[K.D.]

Hi. I have an ongoing pump problem, which I can't figure out. Bear with me, as I am trying to incorporate as much detail as possible.
Washer is 8 years old. Its a Power Play Hot Rod machine, with a B&S engine over a vertical 3 leg under mounted Annovi Reverbi 2.2 GPM pump.
Engine running perfectly.
What's happening -
Start up engine with no water coming to machine, all is fine. Turn on water and when water pressure hits it, engine stalls out. Hold lance trigger down, with water on and start, machine operates with good pressure, but upon releasing trigger, engine goes under load and stalls out. On occasion the machine will behave normally, and idle when trigger is released, but then return to doing the same thing again, maybe the next time, or a few minutes later.
What I have done -
Contracted the makers. They suggested it was the unloader valve. Removed, cleaned greased (silicone grease) and replaced 2 broken O rings. Reassembled everything, and ran it. The first time, it was perfect. The next time, it was back to square 1. Finally I decided to replace the unloader valve with brand new genuine one. Again, the poblem persists. It would appear the unloader is not the issue.
So after all that, does anyone have an idea what might be going on, as I'm all out of ideas.
Thanks in advance.

 

[tabora]

Start up engine with no water coming to machine, all is fine.

Everything I have ever read says that you NEVER start a pressure washer engine until the water is on and all the air has been purged from the system. Does your Owners Manual specifically contradict that?

This is from the HotRod HR230HR24PPLSEZ manual:

ALWAYS turn the water supply “ON ” before turning​

the power washer power to “ON”. Running the​

pump dry of water will cause damage to the internal​

components and render the pressure washer​

inoperable.​

 

[K.D.]

Hi thanks for the replies. Just to clarify, what you have said is 100% correct about not starting without water already running to the pump. What I was trying to show is that if the water is already present, prior to start up, and the trigger is not depressed, it is impossible to crank the engine over as it is also turning the pump which is pressurized with the water. However, if water isn't present, the engine can be started, and then if water is turned on, the pump basically brings the engine to stall. The other option is to apply water , depress the trigger on the lance, so that there is water flowing and THEN crank the engine. This results in a start and straight through to pressure out of the nozzle, which is OK until you release the trigger, then the engine is stalled by whatever is going on with the pump ( it would suggest the unloader valve, but after cleaning the original and then replacing it, the problem still persists} Just to be clear, I am aware of water before start, which is how I have always started a power washer ( this past 30+ years) , but as as an illustration of how I was trying to narrow down the problem, I started first and then applied water. It is always at the point of the pump getting incoming water pressure, that it loads the engine to the point of stalling. Therein lies the problem, but the unloader vavle does not appear to be it.

 

[tabora]

but as as an illustration of how I was trying to narrow down the problem, I started first and then applied water.

But if you started the pump EVEN ONCE without water in it, the unloader valve may be toast. You said:

Reassembled everything, and ran it. The first time, it was perfect. The next time, it was back to square 1. Finally I decided to replace the unloader valve with brand new genuine one. Again, the poblem persists. It would appear the unloader is not the issue.

 

[K.D.]

Fair point. So why would it work, then not work then work, if it's fried?

 

[tabora]

What happens when unloader valves fail?

A failing unloader valve is immediately noticeable because of its critical impact on the performance of pressure pumps. Unloader valves that aren't working properly can cause these problems:

• Pump motor stalling – if a pump is powered by a gasoline or diesel engine, stalling whenever the operator ceases to use it is a good sign of unloader valve failure. The buildup of pressure locks the pump's internal components, which in turn prevents the rotation of the powered engine shaft. Such a problem indicates the unloader valve is not properly recirculating water back into the pump.
• No pressurized water available – an unloader valve that is stuck in the bypass position will prevent water from entering the pressure hose and nozzle. If your pump's engine is functioning properly, an adequate supply of water is entering the system, and there are no leaks in your system, then an unloader valve failure is a strong possibility when you have no access to pressurized water.

What does an unloader valve do?

• The unloader valve serves as a gatekeeper for the flow of pressurized water within a pump before it passes out of the exit hose and pressure nozzle. Unloader valves automatically regulate when water flows into the nozzle or recirculates back into a pump during periods of non-use. During non-use, the water inside the pump becomes a closed loop with no "new" water allowed to enter. Once the operator begins releasing pressurized water again, the unloader valve then stops closed circulation and allows fresh water to enter the system.
• Pressure pumps use positive displacement technology, which simply means that water continuously moves through pumps, as opposed to impulse pumps which only operate in an on or off fashion. With positive displacement pumps, an unloader valve is necessary because it prevents the pump from building destructive internal pressures.