Don't mess with the governor!

[Auto Doc's]

Hello Folks,

The first thing people think when they see a governor arm moving back and forth on an engine with a surging problem is the governor needs to be adjusted. Wrong!

It's not the governor causing this problem. The governor is only reacting to a carburetor problem.

For some odd reason people think that they have to mess with a governor adjustment to resolve a surging engine problem.

STOP! Messing with a governor shaft adjustment. You can actually cause worse problems instead of helping the situation.

The governor only has one job and that is to keep the engine from running beyond a safe mechanical limit and blowing itself apart.

An engine surging problem has to do with a possible air leak after the throttle plate, a worn throttle shaft or a bleed air jet passage that has become restricted.

Some governor arms may have multiple holes for the tension spring to fit, that is normal so the appropriate hole can be used to set the top running RPM of the engine.

A portable generator is a good example of this. The generator has to be able to run at 60 Hz for proper "ideal" voltage output here in the U.S. If the generator were used in Canada or some other countries the spring location on the governor arm would have to be changed so the generator would run at 50 Hz.

 

[StarTech]

I have to disagree here. There are times that a governor can cause surging especially with systems that has too much slop in the system. Now this is on the rare side but it is possible. And top of that when a carburetors are remove and reinstall there are cases where the adjustment changes. I even know a few Kohler Courage single cylinder where I had to intentionally set the static governor adjustment off by 0.010" to stop surging which is caused by the governor itself. On top of that a governor idle setup can be maladjusted by inexperienced DIYers causing those engines to go into runaway mode when there is nothing wrong with the governor or carburetor other than a simple adjustment problem.

Why do you think of these systems have anti surge springs on the linkages? Just to look pretty? It is to remove slack in the linkages as they wear which can cause surging.

This is why a static governor adjust should be preformed to simply to rule out a miss adjusted governor as we never know what the previous person has done. Dynamic governor adjustment is a different animal than static adjustment. This why there is so many governor springs out there. Every engine model has its own complete governor setup run at a particular spec. For example generators has to have a setup that is more responsive to smaller rpm changes than say a lawn mower engine. This is why a generator has governor that are usually sensitive to less than a 1% rpm change. At 60hz this is 150 rpm and at 50hz it is even a smaller rpm change.

 

[Tiger Small Engine]

Hello Folks,

The first thing people think when they see a governor arm moving back and forth on an engine with a surging problem is the governor needs to be adjusted. Wrong!

It's not the governor causing this problem. The governor is only reacting to a carburetor problem.

For some odd reason people think that they have to mess with a governor adjustment to resolve a surging engine problem.

STOP! Messing with a governor shaft adjustment. You can actually cause worse problems instead of helping the situation.

The governor only has one job and that is to keep the engine from running beyond a safe mechanical limit and blowing itself apart.

An engine surging problem has to do with a possible air leak after the throttle plate, a worn throttle shaft or a bleed air jet passage that has become restricted.

Some governor arms may have multiple holes for the tension spring to fit, that is normal so the appropriate hole can be used to set the top running RPM of the engine.

A portable generator is a good example of this. The generator has to be able to run at 60 Hz for proper "ideal" voltage output here in the U.S. If the generator were used in Canada or some other countries the spring location on the governor arm would have to be changed so the generator would run at 50 Hz.

Don’t forget the emulsion tube, pilot jet, and main jet also getting blocked partially or fully is what mainly leads to hunting and surging. It is normally lack of fuel (running lean) that causes RPM fluctuation. Occasionally it can be air leaks in intake gasket, etc.
Rarely is it a governor adjustment.

 

[StarTech]

If you really want to get technical in the case of Nikki carburetors it can be a case of over rich fuel mixture slowing the engine too much and the governor opening the throttle vane going into an over speed condition which then the governor tries to slow back down to the set idle speed thus causing the cycling. This is primary cause by the jet(s) being loose at idle, allowing excess fuel to bypass the jets; and then sealing as the engine speed increases above the set idle speed and as engine burns off the excess fuel while the throttle vane too open.

The reason to check the static governor adjustment is to rule out that possibility and verify you actually have a fuel related problem. Simply to do and its only a couple minutes to do. It just like doing voltage drop tests, it is to rule out a possible problem so you can focus on other possible causes.

Besides even if the carburetor, governor are fine; and there is no air leaks there other things that cause surging such as a failing spark plug. Sometimes you got to think outside the box. This is why non invasive are done in the first place as rule out possible causes.

I had this very problem with a JD E110 last year. And it started with a failed ACR. Customer installed a starter which cause the stator to short out and fried the voltage regulator. From the engine was idling fine at start up until you engaged the deck. It surge like crazy even you disengaged the deck. I changed the carb thinking I clogged circuit but it kept doing this. In the middle of the night woke up with a possible cause and solution.

 

[Auto Doc's]

Hi StarTech and TSM,

I'm glad we have a few experienced folks on this site like yourselves. I am also grateful that y'all are bringing up some of the very points concerning a surging problem aside from tinkering with a governor.

This past season, I have had to pull several engines and open the up because the DIY owner went the wrong direction while playing with a governor shaft adjustment.

 

[StarTech]

When DIYer screws up it only costs them more money as the extra time and parts we all have put in undoing their mistakes just to get to the real problem and fix the new damages. I hate having to fix problems that weren't the problem to start with but I do charge for doing it.

Most DIYers just don't understand that we put a lot time and money into learning what we know how to do. This don't even count our normal day to day operating expenses. My labor rate is lower only because I don't have the overhead of a standalone brick and mortar shop with employees. It doesn't mean I don't know what I am doing.

 

[woodstover]

Hello Folks,

The first thing people think when they see a governor arm moving back and forth on an engine with a surging problem is the governor needs to be adjusted. Wrong!

It's not the governor causing this problem. The governor is only reacting to a carburetor problem.

For some odd reason people think that they have to mess with a governor adjustment to resolve a surging engine problem.

STOP! Messing with a governor shaft adjustment. You can actually cause worse problems instead of helping the situation.

The governor only has one job and that is to keep the engine from running beyond a safe mechanical limit and blowing itself apart.

An engine surging problem has to do with a possible air leak after the throttle plate, a worn throttle shaft or a bleed air jet passage that has become restricted.

Some governor arms may have multiple holes for the tension spring to fit, that is normal so the appropriate hole can be used to set the top running RPM of the engine.

A portable generator is a good example of this. The generator has to be able to run at 60 Hz for proper "ideal" voltage output here in the U.S. If the generator were used in Canada or some other countries the spring location on the governor arm would have to be changed so the generator would run at 50 Hz.

We are 60hz here in Canada LOL

 

[Auto Doc's]

We are 60hz here in Canada LOL

Thanks for the info woodstover.

Is that all of Canada now? I've been told there were different areas that were 50Hz.

I'm down here in deep South Texas and I don't visit other parts of the world like a use to.

 

[woodstover]

Thanks for the info woodstover.

Is that all of Canada now? I've been told there were different areas that were 50Hz.

I'm down here in deep South Texas and I don't visit other parts of the world like a use to.

We are 60hz countrywide if you're hooked to the grid