Pressure washer "surge" question

[TT_Vert]

I have a ryobi RY80940B 3,100 PSI pressure washer w/ a honda engine that seems to be acting strange lately. It always starts up perfectly but has a surge issue and also an issue w/ the RPM ramp up on occasion. I've looked at the exploded daigs to understand a bit more about how the governor works, etc but i'm confused what would be causing my issue. I have two issues actually. This pressure washer has an idle up feature that is supposed to bring up the RPMS when squeezing the trigger, is this monitored and controlled by a pressure change or water flow somehow?

This issues

1. As you can see in the video I get an rpm surge where I think the governor is moving (Hard to see in video). It repeats this continually. I thought maybe I had an air/fuel issue so I pulled the filter off but the problem persisted.
2. When i first start it many times i'll not ramp up rpms for sometimes a few minutes when squeezing the trigger. After it starts to ramp up as designed it's usually fine. Oddly many times if I squeeze it and let go it'll ramp up for a sec so I guess I need to better understand the design of this ramp up function to fix this.

Here is a video of what it is doing.

The unloader valve moves freely and looks brand new also.

Thanks much

Dave

 

[Showkey]

Surging is more likely a fuel mixture problem and NOT the governor. Clean the carb ......the jets are partially plugged with crab. ( likely from ethanol fuel storage....very very common) keeps the small engine guys in business.

 

[TT_Vert]

Surging is more likely a fuel mixture problem and NOT the governor. Clean the carb ......the jets are partially plugged with crab. ( likely from ethanol fuel storage....very very common) keeps the small engine guys in business.

Yeah I thought it was a mixture problem too that's why I figured it was a clogged air filter. If it was a mixture issue wouldn't it have a bit of a problem starting? I always turn the fuel off when I store it for the winter and run it out but I suppose I'll pull the carb and take a look at the jet.

Dave

 

[American Locomotive]

Doesn't look like a governor or fuel mixture issue to me. It looks like whatever controls the governor/throttle setting is messing up.

 

[tarmy]

The other thing that causes this is air in the pump...or coming into to pump via the water being delivered The surge is caused by the air compressing easier than water and that allows the engine to rev up a bit until the water is the only thing being compressed.

Check your watersystem...are you on a well by chance?

 

[Bretny]

No you wont have a starting problem. Theres a small jet thats dirty or clogged. Not the main jet with the needle.

 

[TT_Vert]

I am on a well but I have good and consistent pressure w/o any obvious air.. I need to find out if if it's a blade type or weight controlled governor.

Dave

 

[theoldwizard1]

Doesn't look like a governor or fuel mixture issue to me. It looks like whatever controls the governor/throttle setting is messing up.

Surging on carbureted small engine is almost always caused by a clogged low speed jet. With the carburetor apart, use a single wire from a wire brush and probe all of the small passages then blow out with cleaner.

Surging on a previously properly running small engine is almost NEVER caused by the governor mechanism.

 

[NUTTSGT]

My riding mower used to do that or something similar. I found the gasket around the fuel solenoid was leaking and filling the solenoid with gasoline. A quick repair with teflon tape and solved the issue.

 

[TT_Vert]

Thanks guys, I'll take the carb about and do a quick visual on it. I am not entirely sure it always does this surge either to be honest but I'll make a note. Anyone have any input on those the idle down features work on the units? Trying to troubleshoot why it doesn't usually idle up when pressing want for first 5 minutes or so without a ton of finagling.

Dave

 

[American Locomotive]

Surging on carbureted small engine is almost always caused by a clogged low speed jet. With the carburetor apart, use a single wire from a wire brush and probe all of the small passages then blow out with cleaner.

Surging on a previously properly running small engine is almost NEVER caused by the governor mechanism.

Watch the video and look at the governor arm. The engine is idling fine, and then the governor arm suddenly fires over to the full throttle position. A quarter second later it instantly fires back the other direction and the engine returns to a steady idle. Then it repeats and does the same thing again.

Carb issue governor hunting does not manifest itself like that. With carb issues (usually lean stumbling from dirty jets), the governor is constantly hunting and moving around. In this case the governor is instantly slamming from one extreme to the other.

You have to look at the big picture, and all of the information that is being provided. He mentioned the pressure washer has a mechanism to reduce engine speed when the pump is unloaded. He also mentioned the mechanism is not working properly, causing the engine to remain at idle speed even pressure washing. After several minutes, it will then go to full speed.

So this pressure washer has a mechanism that is capable of controlling the governed engine speed. This mechanism clearly isn't functioning properly. We also have an issue with the engine "surging" at idle, but we see that it isn't typical lean-burn surge, and the governor arm is acting erratically. What can cause the governor arm to react like that? Wildly varying throttle inputs. Which brings us back to the idle-down mechanism.

 

[Bluejoe]

The tiny passages of carburetor are clogged. It’s probably load idle jet. It’s located under the black in color idle screw. Remove plastic screw then pullout the jet. It has a very tiny hole at the bottom which gets clogged. The thickness of wire to fit probably size of a piece of hair. The other problem would be once you pull the jet out check the two o-rings. The top one really never a problem but the bottom one get deformed over time and rips. Sometimes. If this happens the carburetor will continue to surge and shutdown.

 

[Showkey]

surging on carbureted small engine is almost always caused by a clogged low speed jet. With the carburetor apart, use a single wire from a wire brush and probe all of the small

surging on a previously properly running small engine is almost never caused by the governor mechanism.

agree

doesn't look like a governor or fuel mixture issue to me. It looks like whatever controls the governor/throttle setting is messing up.

disagree

 

[TT_Vert]

I also have a feeling it's the idle down mechanism which is why I'm trying to figure out exactly how that works. I can tear it down and try to figure it out but I'm hoping someone else has an idea so I can wrap my head around it before I start tearing it down. That plus the fact it doesn't idle up properly for the first few minutes when trigger is pulled I feel it's that. Just don't want to go into it blind if I don't have to.

Dave

 

[theoldwizard1]

i also have a feeling it's the idle down mechanism which is why i'm trying to figure out exactly how that works.

it is highly unlikely that it is a linkage issue !

 

[TT_Vert]

I don't think it's the mechanical linkage but the interface between the two in another way. If i knew how the system operated I'd have a better idea but i think it used water flow or pressure differential to idle it up and down. How else would it idle up when the trigger is pulled other than the sudden variance in flow/pressure? I feel that is where the problem may lie but I cannot find any real info on how that system operates. This would explain the surges as it is detecting an erroneous trigger pull and idling up for a second.

Dave

 

[American Locomotive]

Every small engine governor has a throttle input somewhere. On fixed-speed engines, it's usually just a spring with a set tension. In your case, it will be a spring with some kind of actuator lever to adjust the tension - the throttle lever.

Looking at some things online, it appears there should be a throttle cable coming from an assembly bolted to the side of the pump going up towards the governor assembly. I would start there - make sure the cable moves freely, unbolt the mechanism and make sure it's not bound up, dirty, etc...

 

[TT_Vert]

And you think a cable/linkage/level is what is allowing the auto idle up/down function of this pressure washer? If that is the case I need to figure out what it detects to determine idle up/down. I'll check all the mechanisms again but everything moved freely when I was messing around w/ it the other day.

It all comes down to me understanding WHAT determines idle up/down. Is it pressure, flow, electrical, etc. that it sees change to allow idle up/down. Surely someone has to know, I cannot believe I cannot find any info on how that operates or even a service manual.

Dave

 

[theoldwizard1]

It all comes down to me understanding WHAT determines idle up/down. Is it pressure, flow, electrical, etc. that it sees change to allow idle up/down. Surely someone has to know, I cannot believe I cannot find any info on how that operates or even a service manual.

The lever that you move to go from idle to full speed is NEVER directly connected to the actual throttle plate inside the carburetor. The throttle plate is directly connected to a linkage that goes to the governor.

The throttle lever is connect to the governor via a light spring. This light spring adds a small amount of additional force to the governor linkage to move it off the idle position. When the engine slows down from a load, the governor opens the throttle to compensate for this loss of RPMs. Most small engines run at about 3600 RPM.

There are several common governor designs. The two most popular are as follows:

The old B&S engines (and many other small engines) used the air flow off of the flywheel fan to move a very lightweight piece of metal on a pivot, often called a sail. There was often a light spring to pull the sail to a position so that the throttle plat was at WOT when the crank was not spinning.

A lot of engines these days use internal "flying weights" that move a plunger in and out, or twist a shaft, through the crankcase. Gravity pulls the weights down so that the throttle is at WOT when the crank is not spinning.



Governor linkages should never be adjusted ! Leave the damn factory linkage alone !! You will just make it worse. If you have to remove the carburetor for clean, make good note of what hole the linkages and spring were in so that yu can re-assemble it correctlky. Most engine still have an idle screw that can be adjusted. Some engines (like the old Tecumsehs) had a screw on the governor linkage "plate" that would adjust the maximum RPM.

Forget the rest of the video, at 24 seconds, this video shows the governor arm (which is attached to the internal governor mechanism).


I guess 40 years of "messing" with small engines, this all seems second nature to me !

 

[ezover]

Yeah I thought it was a mixture problem too that's why I figured it was a clogged air filter. If it was a mixture issue wouldn't it have a bit of a problem starting? I always turn the fuel off when I store it for the winter and run it out but I suppose I'll pull the carb and take a look at the jet.

Dave

make the switch to rec. fuel for your small engines.

 

[TT_Vert]

The lever that you move to go from idle to full speed is NEVER directly connected to the actual throttle plate inside the carburetor. The throttle plate is directly connected to a linkage that goes to the governor.

The throttle lever is connect to the governor via a light spring. This light spring adds a small amount of additional force to the governor linkage to move it off the idle position. When the engine slows down from a load, the governor opens the throttle to compensate for this loss of RPMs. Most small engines run at about 3600 RPM.

There are several common governor designs. The two most popular are as follows:

The old B&S engines (and many other small engines) used the air flow off of the flywheel fan to move a very lightweight piece of metal on a pivot, often called a sail. There was often a light spring to pull the sail to a position so that the throttle plat was at WOT when the crank was not spinning.

A lot of engines these days use internal "flying weights" that move a plunger in and out, or twist a shaft, through the crankcase. Gravity pulls the weights down so that the throttle is at WOT when the crank is not spinning.



Governor linkages should never be adjusted ! Leave the damn factory linkage alone !! You will just make it worse. If you have to remove the carburetor for clean, make good note of what hole the linkages and spring were in so that yu can re-assemble it correctlky. Most engine still have an idle screw that can be adjusted. Some engines (like the old Tecumsehs) had a screw on the governor linkage "plate" that would adjust the maximum RPM.

Forget the rest of the video, at 24 seconds, this video shows the governor arm (which is attached to the internal governor mechanism).


I guess 40 years of "messing" with small engines, this all seems second nature to me !

I am not being too clear i don't think. I know how the governor works. I am just trying to figure out WHAT determines that it should idle up/down. It idles up when I pull the trigger and idles down when I let go. Is it still just engine load that is causing this idle up? It detects more engine load due to request for water (And thus pump load) to the sprayer nozzle by pulling the trigger and then it just acts on the governor arm?

Dave

 

[TT_Vert]

make the switch to rec. fuel for your small engines.

According to the purefuel app there is 1 place that has rec fuel and it is 20 miles away so that's a no go for me. I guess that's to be expected in the crappy state of Illinois these days.
Dave

 

[American Locomotive]

I am not being too clear i don't think. I know how the governor works. I am just trying to figure out WHAT determines that it should idle up/down. It idles up when I pull the trigger and idles down when I let go. Is it still just engine load that is causing this idle up? It detects more engine load due to request for water (And thus pump load) to the sprayer nozzle by pulling the trigger and then it just acts on the governor arm?

Dave

Just go out and look at your pressure washer. I already told you what it uses. There's a throttle cable coming from a device bolted to the pump. The device on the pump is what is controlling the engine's throttle. It's likely powered by some pressure circuit inside the pump.

 

[TT_Vert]

Just go out and look at your pressure washer. I already told you what it uses. There's a throttle cable coming from a device bolted to the pump. The device on the pump is what is controlling the engine's throttle. It's likely powered by some pressure circuit inside the pump.

Actually after looking where the hose output is and where the unloader is there is a cable that goes to the governor. right from there I need to find out what signals that to increase the throttle now. If it is in fact pressure the question I need to find out is how does this pressure circuit control the pressure which is what my initial question was. Does it see differential in pressure? Does it use a minor change in pressure, is it just a venturi effect of some sort? I'm fairly sure whatever pressure sensing it is doing is what is not only causing the periodic surge (It didn't do that today) it is also the reason that many times when I pull the trigger or even have it pulled it does not increase idle/build pressure or kills the pressure mid squeeze even though it idled up properly. And without a service manual I'll just be guessing I assume.

Finally found some more detailed info. So basically it senses a pressure drop at the outlet which feeds a circuit w/ an actuator to pull the cable in to increase RPM. Now I just need to find out why this circuit is working intermittently. I'd think if it was a blockage in a passage it'd do it consistently but there is zero consistency to this problem. The water inlet also has a filter which should prevent most debris from causing an issue.

An idle down controller for pressure washers is responsive to the drop in pressure at the pump outlet. The controller includes a sensor disposed in the pump outlet manifold. When the fluid is being bypassed, the manifold pressure drop is communicated to an actuator. The actuator overrides the engine governor and forces the engine throttle to the idle speed. When an operator is discharging a pressurized fluid, the actuator allows the governor to operate the engine at its normal speed.

This pic makes it easy to understand.
https://patentimages.storage.googleapis.com/13/19/1f/fd42dc5a959108/US08038413-20111018-D00009.png

Dave

 

[American Locomotive]

I don't think it's necessarily looking for a "pressure drop", it appears to be comparing the internal pump pressure to the outlet pressure. If the outlet pressure is greater than the internal pump manifold pressure, the engine idles. If the manifold pressure is greater than the outlet pressure, the engine goes to full speed.

It could be a blocked passage, a leaking piston seal on the actuator, or a leak somewhere on the outlet or internal pump manifold. It could even just be a sticky actuator due to corrosion.

 

[TT_Vert]

I'll have to tear it down and see. Is this differential pressure usually detecting pressure w/ a physical switch of some sort? The fact that is this intermittent is what baffles me. This is very descriptive and I'm trying to wrap my head around it..
https://patents.google.com/patent/US8038413

Dave

 

[American Locomotive]

In that particular patent, the device is not working on differential pressure. It's simply sensing the internal pump manifold pressure (before the unloading valve). When unloaded, there is very little pressure there. Once loaded up, high pressure exists which then actuates the idle control to full throttle.

However I wouldn't read too much into that patent. That patent is just for one implementation, and there is no guarantee yours is the same.