Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

Old, Old, Lawn Boy Governor Problem?


zoomzoom's Avatar
Member

Join Date: Jul 2002
Posts: 36
PA

05-07-04, 02:16 PM   #1  
Old, Old, Lawn Boy Governor Problem?

I have a model 5231, engine D-400 (purchased in 1963) Lawn Boy push mower which has been running great except for the fact that the high speed or deep grass mode was not functioning, i.e., not changing speed in either position. I removed the flywheel and found that one of the governor weights had detached itself from the governor yoke and consequently become damaged by the rotating flywheel.

Seeing no additional damage to other governor parts, I purchased a new governor weight for this model, cleaned the parts, lubed the thrust washer and then reassembled the governor making sure to correctly install the nylon collar on the governor lever. Since I dont have a governor gauge, a visual check was performed to see that all parts were free to move without sticking. I then installed the flywheel and started the machine.

The mower now idles at very low speed for several minutes -- the time is random, and suddenly comes up to a higher speed all by itself. The high speed feature still doesn't work.

Mowing is satisfactory unless I accidently move too quickly into deep grass. If the engine slows to too low of a rpm then it falls back into what I call the "putt-putt" mode and usually stay there until I get disgusted and put it away until another day.

My diagnostic evaluation has only included: taking the governor apart several time to satisfy myself that it isn't sticking or hanging up internally (doesn't appear to be), manually moving the governor to carb rod trying to increase the rpm (it didn't), removing the air cleaner to note change in rpm (it doesn't) and giving the running engine a squirt of starting fluid just to satisfy myself that fuel is not a problem (had no effect on rpm). Note that I have not looked at other major components like reed valves, etc.

I'd really like to keep using this fine machine so any tips or suggesting would be greatly appreciated.

thanks,

barry

 
Sponsored Links
puey61's Avatar
Member

Join Date: Apr 2004
Posts: 3,224
NY

05-07-04, 03:47 PM   #2  
Old dog

It is difficult to tell by your description whether you have a power (lack of) or governor problem. Since it appears you have covered all bases regarding the governor, you may well have power issues, particularly within the engine. I recommend removing the muffler to inspect the exhaust port as well as the piston & cylinder. You may find either excessive carbon build-up in the port or possibly piston/cylinder scoring or both. If it turns out to be only carbon, use a small screwdriver to chip this out being careful not to damage the piston in the process. You will want to position the piston so that it is covering the port hole so that no carbon chips make their way into the cylinder. As far as your reed go, a tell-tale sign of trouble with any of these would be a mist of fuel spitting back out of the carburetor when the engine is running. Also refer to https://lookup2.toro.com/partdex/ind...Caller=lawnboy and enter your model # and this will give you an exploded view break-down of your machine, paying close attention to the governor components. Let us know how it goes.

 
jughead's Avatar
Member

Join Date: Oct 2003
Posts: 597

05-07-04, 04:38 PM   #3  
What about the governor spring?? When the mower is sitting with the engine off the throttle should be full open. The flyweights serve to move the throttle towards the closed position and the spring moves the throttle towards the open position. If something is messed up with the governor spring the throttle won't open and give you more power when the engine load increases. When you first start the engine the throttle should be open fully and then when the engine speed starts to pick up the flyweights move out and as they do so the throttle is retarded to maintain a setpoint speed. From your description is sounds like either the spring is disconnected, and/or missing, or the governor linkage is misadjusted. Governors aren't well understood and can be difficult to adjust right if you don't fully understand how they are supposed to work. When you are changing to "deep grass mode" all you should be doing is changing the tension on the governor spring. It's the governor that actually manipulates the throttle. The user "throttle" is nothing but a speed control that changes the setpoint of the governor.

 
Terminator20's Avatar
Member

Join Date: Aug 2003
Posts: 865

05-07-04, 05:28 PM   #4  
If you are mowing and hit a patch of heavy grass your engine will slow down and the governor will sense that and advance your throttle to bring the speed back to the set point. The governor will indeed force the engine to full throttle when the load is heavy but won't do so when running unloaded to keep the engine from overspeeding. Bad things can happen to any engine when it runs at an excessive speed. Many larger engines have overspeed trips because if something breaks and the load drops off suddenly while the engine is at full throttle the governor won't be able to reduce the throttle fast enough to keep the engine glued together. Piston rods have been known to knock a large hole in the block after breaking due to an overspeed condition. Something like that could happen to a belt driven mower if a belt should break and you didn't have a working governor.

 
cheese's Avatar
Forum Topic Moderator

Join Date: Jul 2001
Posts: 16,567
GA

05-07-04, 11:52 PM   #5  
Hello Zoomzoom!

Not saying you don't have a governor problem, but it does sound like you covered the bases with that. If moving the throttle manually still doesn't increase the RPM, then the governor isn't the problem, or at least the entire problem.

I agree with Puey61. The exhaust port, especially on these old lawnboys, is a common problem area for blockage. You'll ahve to remove the muffler and make sure it is cleared out and the port is clear. It sounds like this may be the problem from your description.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
Terminator20's Avatar
Member

Join Date: Aug 2003
Posts: 865

05-09-04, 08:16 PM   #6  
Did you get it fixed?

 
zoomzoom's Avatar
Member

Join Date: Jul 2002
Posts: 36
PA

05-10-04, 05:45 AM   #7  
Terminator asked if I had figured out the old Lawn Boy governer problem yet. Well, this weekend my wife wanted the trim replaced on the front door and I wanted to work on the mower. Guess which one got done!

I'm going to check out the carbon in the exhaust port and the reed valve suggestion and promise to report back.

My thanks to all who have shared their knowledge

 
zoomzoom's Avatar
Member

Join Date: Jul 2002
Posts: 36
PA

05-13-04, 10:58 AM   #8  
Update on old lawn boy problem

Thanks to all for the suggestions,

Here is what I did.

1. Cleaned the carbon out of the exhaust port. I'd estimate that the port was obstructed by 30%. Engine now has more power but this didn't solve the "putt putt problem.

2. Checked the governer assemble for binding. Everything seems to be OK and the throttle plate is wide open when the engine is not running.

When the engine is started it runs at a low rpm for several minutes and then suddenly increases to normal rpm almost as if someone flipped a switch.

When it decides to increase rpm it has lots of power for mowing but if I happen to overload the engine in high grass and the rpms drop too low, I'm back into the putt putt mode for several minutes. If I then let the mower run at the low, putt putt speed the mower will eventually speed up to normal rpm again.

Any chance this could be a intermittent in the coil or condenser? When it's in the putt putt mode it looks like the plug is firing on every other crank revolution instead of every revolution.

Or perhaps, it is inhabited by an alien life force?

 
Terminator20's Avatar
Member

Join Date: Aug 2003
Posts: 865

05-13-04, 01:21 PM   #9  
From your last post it seems to me that you have a ignition problem going on here. If it runs well at idle for a period of time and then all of the sudden it increases its speed? That sounds like the coil playing tricks on you. All coils I have seen in my life that go out, they go out in mysterious ways. If a coil stops giving spark aftor its been heated up, could also give more spark then needed. Its a big possibility. I would get a spark diagnostic tool to see if the coil is giving the proper spark aftor its been heated up. Just a thought. Many opinions to be given here. Let us know how it goes.

 
puey61's Avatar
Member

Join Date: Apr 2004
Posts: 3,224
NY

05-13-04, 02:54 PM   #10  
Good job thus far!

Based on your last post, I now believe you definitely have a governor related problem. This is a very complicated system and to help you without being with you will be near impossible. Have you yet checked the Lawn-Boy website and compared your machine against the break-down on their site? It sounds to me as though something may be missing or worn badly. Unless you replace all governor components with new, you may well have to take the machine to an authorized dealer for their expertise. Good luck and let us know.

 
jughead's Avatar
Member

Join Date: Oct 2003
Posts: 597

05-13-04, 04:10 PM   #11  
Interesting problem. If the engine we are talking about is a 4 stroke/cycle type then you will only have 1 power stroke for every 2 revolutions of the shaft. I think the only way to resolve the question: is it a governor problem OR is it an ignition system problem OR is it a carburation problem ????? is to watch what happens to the governor - - throttle linkage when the engine goes into what you call the "putt-putt" mode. In that mode the governor should be calling for full throttle. If you see that the governor-throttle linkage actually is at or near the full throttle postion, then I would say your problems ARE NOT governor related. On the other hand, if you see that the governor is NOT calling for full throttle when the engine in just putt-putting, then I would look for something binding, or sticking in the governor-throttle linkage system. You need to make this simple test so you can focus your troubleshooting efforts onto the system that is really the source of the problem. Since you say that the throttle is at full with the engine off it sounds like the governor may be doing it's thing. Also, if the governor was screwing up, the engine would most likely be running smoothly but at a slow idle. I'm starting to become a member of the "ignition problems" camp here, but please try my suggested test and let us know what you find.

 
cheese's Avatar
Forum Topic Moderator

Join Date: Jul 2001
Posts: 16,567
GA

05-14-04, 01:14 AM   #12  
I just realized...this is an old lawn boy, with a 2 storke engine. If the air-fuel ratio is a bit rich, it will sputter, then suddenly run like a banshee, then sputter again. Sometimes it will jump from one to another rather quickly, sometimes not. Will always sputter until it warms up. I think you need to turn the mixture screw in a little.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
Terminator20's Avatar
Member

Join Date: Aug 2003
Posts: 865

05-14-04, 09:13 AM   #13  
Oh, I thought it was a 4-stroke. That changes things a bit. Yes, make sure its not running too rich. Other sypmtoms of a too rich condition are, Carbon buildup, less power, and just one big mess to deal with. Let us know how it goes.

 
Search this Thread