Ryobi pressure washer

[Mr Mower Man]

A customer brought in his Ryobi 3100 PSI pressure washer (RY80940) with the complaint that the engine RPM's didn't pick up when he squeezed the trigger on the wand. Turns out that he let it sit for a few months before he decided to bring it here, so it wouldn't run at all by the time I got it. He approved a new carburetor, which I then replaced, and the engine runs perfectly. But the idle down function seems to work backwards sometimes, and not at all sometimes. There's not a definite pattern to how it works. But I also noticed that the water pressure couldn't have been anywhere near 3100 PSI. I have a Briggs & Stratton 3000 PSI pressure washer that will break skin if you get too close to the nozzle. The water output from this Ryobi is much weaker, even at high engine RPM's. I'm assuming these two problems (low pressure and idle down feature) are related, but I'm not exactly clear on how the idle down feature operates. A brand new pump is right at $100, so I'm not inclined to spend too much time & effort figuring out the problem rather than replacing the pump. But if any of you have more experience with these water pumps and could help me quickly pinpoint the problem, that would be helpful.

Thanks!

[bgsengine]

actually engine should not idle down when the trigger is squeezed- that is the load, engine should actually slow a bit when trigger squeezed, then pick up as the governor compensates for load. when not in use the engine is just moving water around in the pump, which is where any idle-down (if any) feature should happen. With those china made "disposables" in many cases you cant even GET parts for the pumps anyway.

[Luffydog]

Possibly the unloader valve going out

[KE4AVB]

I just wondering what they calling auto idle feature. Here on the larger 4000 psi 3.5 and 4.0 gpm pumps they don't into full idle but do the same as any governed engine. They simply throttle back to the idle circuits of the carburetor as the unloader is active and then go to full throttle under load. I need to know more about this setup to know what is going as there several different type of unloader and all act differently. There is one called the easy start that unloads nearly completely at startup rpms.

As for not operating full pressure the first thing I check is to make the customer is using the correct tips. This can make a world difference in the output pressure and engine loading. For example and I am referencing a Cat 6DX 4000 psi / 4 gpm pump here if you have 4000 psi 4.5 gpm tip it will not produce the same output as if you use the correct 4000 psi 4.0 gpm tip. Actually you will have less than 3000 psi with 4.5 gpm zero degree tip vs 4000 psi with 4.0 gpm zero degree tip. My customer is running these pumps with the Honda GX390 and the 4.0 gpm tips severely loads the GX390 if the pressure regulator is crank up to 4000 psi. Oh it can drive the pump but it does struggle to do it. It just that the 13hp is a little small to run these pumps. My other customer is using a Honda V-twin to drive same pumps and they have no problem driving the pumps.

For a test and this is provide your other pressure washer pump have the same output hose fitting is to use it. When comparing output you got to compare apples to apples and you should have a good test pressure gauge inline. It only takes one leaky o-ring or check valve to cause a big loss of pressure. Also make sure the pressure regulator is max out as the customer may have lowered the output pressure to their desired pressure level.

But as you have already found out these vertical pumps are fairly cheap and manufacture do put on the cheapest pump they can. I see many that have failed and when the customer is willing I install better pump that carries a 5 year warranty. Now as BGS said most of cheaper pumps are not even repairable due lack of available parts. Even those the can be repaired it can difficult to do it if you have to replace an oil seal as some requires using a press just to get them back together due the spring load(s).

[Elader]

Possibly the unloader valve going out

We've seen almost the same case causing by unloader valve acting.

[RoyM]

Some of the newer unitss have an idle down feature. When the gun is closed and the unloader opens, low water pressure is applied to a plunger that forces the throttle arm back. When the gun is opened normal governor action resumes. By any chance is the inlet screen partially clogged?

[KE4AVB]

Ahhh I was figuring it had something to with the unloader. Just something else I got to watch out for that can cause problems.