OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Troy Built Pressure washer

Hello
I have a Troy Built pressure washer that's runs full out with water pressure applied. This unit has been working okay, it has good water pressure going in and good pressure out. When I am using it the idle will settle down to where I have the throttle set. As soon as I release the trigger on the pressure gun the idle runs full bore, if I leave it running that way, it will shut the engine down, which is a good thing.
I know that the washer will do this if there is no water hose or water applied to the inlet of the washer. This what it's acting like now with water hose applied. The engine governor seems to be working it's also like its working in reverse. Also I did check to make nothing is hanging up on the throttle linkage.
The model no 0902
Briggs & Stratton Quantum 6.5 engine
2350 PSI
2.0 GPM
Thanks for any help on this.
Mike

Hi top, welcome back.

Troy Built equipment is not sold here in Australia as far as I know, but the systems are likely to be generally similar to the pressure washers we see here. Where there are differences, we'll have to rely on asking questions and working out what is going on, together.

Let me tell you how the pressure washers I'm used to, work. After you apply water pressure, you start the engine. You should never start the engine without water pressure applied, because it would ruin the pump. I've never tried doing it, to see whether the engine stops automatically, because I don't want a ruined pump.

As long as there is pressure at the pump inlet, the engine runs at governed speed. There is a screw adjustment to set the governed speed, but it is usually a good idea to follow the manufacturer's recommendations. If the spray wand is shut off (that is, the trigger is not pulled) the pump automatically bypasses because if it didn't, the water would boil in the pump and there would be cavitation damage. Consequently the engine is running at governed speed, but under hardly any load, so it runs fairly quietly. When you pull the trigger on the spray wand, water flows through the pump and the engine has work to do, raising the water from the water supply pressure of about 60 psi, to the pump output pressure, which is 2,400 psi usually if it is a pump with a 5-6 hp engine. Because the engine is suddenly working hard, whenever you pull the trigger the engine's governor opens the throttle and the exhaust noise increases greatly, but the actual speed stays the same. When you release the trigger, it quietens down again.

Now, does your pressure washer do the things I've described? If it does, it sounds as if it is working properly.

Hi Grumpy
Good to have you looking at this with me. Winter is almost over and I will get the lawn mower out that we worked on.
Anyway back to the pressure washer, I understand the principles of the operation. The pressure washer runs full out when the trigger is released and than the engine shuts off. With the trigger pulled the engine settles down and operates normally with good water pressure. Could there be something wrong with the bypass valve? I've checked the governor linkage and it appears to be okay.
Top

I haven't understood the problem yet, Top. Here are the two typical types of bypass valve:
http://www.generalpump.com/PDFs/Unloaders.pdf

Neither valve is shown with a no-water safety shut-off of the engine, but it would not be difficult to add a pressure switch on the intake side of either of them, to actuate the engine's kill switch if there is no water-main pressure there.

The type of unloader I'm more or less familiar with is the first one, the Trapped Pressure type. That type of unloader just senses that the outlet pressure has become unrealistically high if the outlet is shut off. The high output pressure triggers the bypass valve, which reduces the pumping pressure to almost nothing, allowing the governor to reduce the engine's throttle opening to maintain governed speed at no load. When the pump pressure drops, water starts to flow backward from the output hose, and that causes the one-way valve on the output side of the valve to shut off, which traps maximum pressure in the hose and wand. If you have this type of valve you will probably notice that after the wand has been shut off, there is a brief surge of very high pressure from the nozzle when you first pull the trigger. After less than a second the pressure is down to its normal level, and the bypass valve closes, while the engine's governor opens its throttle to maintain the pressure and flow. Of course you will notice the large increase in the engine's exhaust noise.

Is that the type of unloader you have? If so, what is it doing that it shouldn't do?

The second type of unloader valve is the Flow Actuated type. It avoids having an over-pressure situation in the output hose and wand when flow is shut off, but it doesn't really unload the pump. It uses a pressure tapping and orifice in the output side of the valve to sense when there is no flow, and when this happens it opens the bypass passage as the other valve does, but it is only a small passage and it maintains full operating pressure from the pump. Hence with this type of valve you would not notice the engine dropping to no load when you stop spraying, and you would not notice an overpressure in the spray when you first pull the spray trigger. However because it is bypassing water at maximum pressure through a small orifice whenever you are not spraying, it would heat the water, which after a while would boil and cause cavitation damage to the pump. This type of valve therefore requires a thermal or time-delay shut-down feature to stop the engine if you let it run for any length of time without pulling the spray trigger.

While I haven't actually owned or used a washer with that type of valve, I'm not in any hurry to do so: it seems to me to be crude and also to be inconvenient for the user. Of course on a pump driven by an electric motor, it could be a good solution.

Do you have that type of valve? If so, what is it doing that it shouldn't do?

Hi Grumpy
Here is a link to the type of pump I have. http://www.ppe-pressure-washer-parts.com/product/2300PSI-L.
I believe I have the first type of pump you described. The problem is that its not idling. I can manually move the throttle on the carburetor (not the red handle control)to lower the RPM but as soon as I take my finger off it the engine speeds up and eventually the engine will shut down if left long enough about 30 seconds.
Hopefully that's helps you
top

If your pressure washer has several interchangeable nozzles to vary the output pressure, or a hand control to vary the pressure, it has the first type of valve. The second type cannot cope with adjustable output pressure.

I need to educate myself as to how your pressure washer is supposed to work, so we can distinguish between what it does correctly, and what it does incorrectly. Can you give me the exact model number please, so I can search on-line for a user manual?

My pressure washer is a Troy built 1902. There is no interchangeable nozzles. I can vary the spay using the nozzle. I guess the only thing to tell you what its not doing, is there is no way to control the engine speed if your not power washing (the trigger is release) no matter where the throttle control is set, once you release the trigger the engine will run wide open. It just will not idle. It is not suppose to do this. It should idle as long as you have water coming into the pump. There is just no control over the engine rpm after you release the trigger.
Top

I downloaded the operator's manual for the 1902-1 model, Top, and aside from a different wand design (adjustable nozzle instead of set of interchangeable nozzles) and having a different engine (side valve Briggs instead of Chinese copy of Honda GXV160) it looks much the same as my Ryobi. As I read the manual it also seems to operate the same way as the Ryobi: constant engine speed unless you intervene manually to change it, and if you let it run without water flow for too long, its thermal bypass will dump some hot water onto the ground. I haven't found any mention of the engine shutting down or dropping to a lower speed.

Have I read the wrong manual, or am I missing something?

Hi Grumpy
You have the correct manual. I just took the pump off the engine and I am going check it over. I am going to check the engine over also. How does the governor work on these engines? Can I bolt the engine back down without the pump on it and run it? I want to try to isolate the problem it's either the engine or the pump.
With your pump can you adjust the engine speed? mine has a lever that you adjust the speed of the engine. If I set it low it runs wide open and it doesn't matter what I do it runs wide open. Its seems to me the governor is not functioning right it just pushes the throttle to the wide open position all the time. I guess I will know more tomorrow when I get the engine bolted down and start it up with no pump on it. To me it should idle where ever set the throttle lever is set.
Thanks
Top

Now we are getting somewhere, Top. The pressure washer does not have any facility that should cause your engine to drop to idle speed - it should run at the speed you set with the control lever, regardless of conditions. If it doesn't, there is a problem in the engine, or the pump is seizing up or otherwise overloading the engine.

My pressure washer has a screwdriver adjustment of the engine's governed speed. It is readily accessible, but the manual does not mention it or refer to adjusting it, and I don't see why anyone would do so except as a tuning procedure, to suit a specific way of using the machine. I don't know why Troy Bilt had an adjustment lever on your governor - they will have had a marketing reason rather than a technical reason I think.

It does sound at the moment as if your engine has a small malfunction. I suggest we move forward as follows:
1. Please post the Model, Type and Code numbers for your engine. They are usually on a sticker on the cooling air cowling somewhere, but there are other places they sometimes put them. The Model number will probably start with 12 and have a total of 6 characters. The Type will have 4 characters, a dash, and two more characters. The Code will have 8 characters. The three numbers (Model, Type and Code) will all be together. When I have those numbers I can refer to the Operator's Manual, Illustrated Parts List, and workshop manual for accurate details of the engine.
2. Provided the engine is still bolted down to the frame of the pressure washer, it is safe to start and run it without the pump attached. I think it will be considerably easier to proceed that way, both to check that it still misbehaves without the pump attached, and then if it does, to diagnose and fix the exact problem.
3. At the moment it sounds as if you have a governor malfunction on the engine. This may be as simple as something jamming the linkage from the speed control lever to the governor plate near the carburetor, or it may be that a lever on the governor plate has become bent, or the governor spring has fallen off. Then again, it may be something else.

Hi Grumpy
I bolted the engine down and started it. Engine ran wide open no control. I took the gas tank off and rope starter and was able to look at the governor linkage all way back to where it attaches to the shaft that comes out of the engine. I think I've located the problem the arm that attaches to the engine shaft appears to be slipping. I tried to tighten it but still slips. So I tried to get a new arm from the local repair shop but I had to order it. I replace a couple other things that need repair on the engine also. I put some Teflon tape on the shaft to see I can fix so that I can test the engine out. How do those governors work and how you adjust the turn radius on shaft to properly set it? If everything turns out okay I am going replace the pump as open it up and the seals are worn and it would be just as easy to replace the pump instead of a repair kit. The kit is 69.00 dollars and the is hundred and twenty dollars and its an upgraded pump.
I let you know what happens on the engine.

Top

Hi Top,

In order for grumpy to give you correct advice on how the governor works, he needs to know exactly what model engine you have....You have missed the first point in his last reply....he needs the Model, Type and Code that will be stamped on you engine air cooling cowl.
Once he has those, he can help diagnose the problem.
Thanks mate,

As Deejay said Top, we need the Model, Type and Code to sort out the engine properly. Meanwhile, the way the governor works is quite simple. Inside the crankcase there is a simple device that spins at engine speed and has centrifugal weights on it. The weights push on a paddle connected to the shaft that governor arm mounts on. The faster the engine spins, the harder the weights try to rotate the governor arm shaft, and thus move the end of the governor arm that is linked to the engine's throttle. The governor arm is pushed toward closing the throttle by that centrifugal mechanism, and it is pulled the other way by the governor spring. The amount of tension on the governor spring is set by the speed control lever on the side of the engine. So, the engine runs with a balance of forces on the throttle: the centrifugal mechanism trying to close it, and the spring trying to open it. If the governor arm is loose on its shaft, the centrifugal mechanism can't push the throttle toward the closed position, but the spring can still pull it toward the open position.

You usually adjust the position of the governor arm on the shaft coming out of the engine by rotating the shaft clockwise as far as it will go, while pulling the arm clockwise as far as it will go (toward full throttle), then tightening the clamp bolt while everything is held in that position. However we need to check how it is done exactly, for your specific engine, by looking in the workshop manual. To do that we need the Model, Type and Code.

Hi all
Sorry I forgot to put the model number in the body of my last message. It is 12Q802-0120-d1.
So here is the latest, I wrapped Teflon tape around the shaft of the governor and re-mounted the governor arm and tighten the locking bolt tight. I started engine and it ran perfectly. So I think I've solved that problem. The old arm could not be tighten down as the hole in the arm had gotten bigger. I just have to wait for the new arm to come in.
I did just as Deejay said to adjust the governor at least preliminary to see if it would hold the rpm speed steady which it did. Let me know if I need to use a different procedure to adjust governor so can I can apply it when I get the new arm.
Thanks
Mike

Here is the Illustrated Parts List for your engine:
http://bsintek.basco.com/BriggsDocumentDisplay/18mnuLXHnfBhU7y.pdf

Here is the Operator's Manual:
http://bsintek.basco.com/BriggsDocumentDisplay/iorpzOJU0HvjhJvcv4.pdf

You didn't post the Code, so I can't tell you when or where your engine was made.

It sounds as if somebody had engaged in ham-handed amateur maintenance at some point, to damage the governor arm like that. The governor adjustment procedure I gave you is pretty standard for both Briggs' and Honda's small vertical mechanical governor engines. The pinch-bolt on the new governor arm should be tightened to just 1.25 lb.ft. (15 inch-pounds, or 2 Newton-meters), if you don't wish to get the same result as the ham-handed person did.

Hi Grumpy
Sorry I thought that number I gave you was everything. I'll check to see if there is another number on the unit. I didn't see anything that said code.
Thanks for the links. I am not sure about that arm. I don't know why but it must have just start slipping and as it did it cause the hole to enlarge to where it couldn't be tighten down. I bought the unit used about 5 or 6 years ago and its been running great up until this happened.
I'll get that number to you. I'd be curious to see how old this unit really is.
Thanks
Top

I don't think it could just start slipping and then enlarge the hole extensively by slipping, Top. Remember it only rotates a few degrees: I can't imagine it wearing much metal away. The important thing is not to over-tighten it, so it will be reliable with the new arm. Inspect the governor shaft where the arm clamps on it though, in case it has been messed up in some way.