Outdoor Power Equipment and Small Engines - Generator Idles Rough

My 5000 watt generator that I have had for ten years has decided to idle rough, This occured suddenly after the machine idled back when the electrcal load decreased. A prilimary inspection revealed the govenor spring was broken. I replaced this spring and the machine still idles rough. I think this broken spring was a symtom, not the problem:wall:
I have removed/ dissambled and inspected the carburetor, but ther are no signs of trouble here. I've had this carb apart before for cleaning and I know what a gummed up carb looks like. It wasn't that long ago that I had did this. I'm confident that the problem lies somewhere in the ignition.:thinker: I've already replaced the spark plug and this didn't solve anything.
Does any one know hopw to trouble shoot the Oil Gard module?
Anybody got any sugestions on how to trouble shoot an intermitent coil?:confused: The ohm reading is 17000 ohms.
Thankls for your suggestions

What do you have?

Generally the ignition or related components (other than the spark plug) don't fail in such a manner as to just cause a rough idle. Usually that is a carb problem. I've cleaned carbs only to have them mess up again in a matter of hours. It doesn't matter how recently it was cleaned, if something gets dislodged from inside the tank or the inner wall of a fuel line and gets through the filter, it's liable to get caught in a jet. It could be as simple as turning a screw, but I don't know what you have to give you any details.

What do you have?

Generally the ignition or related components (other than the spark plug) don't fail in such a manner as to just cause a rough idle. Usually that is a carb problem. I've cleaned carbs only to have them mess up again in a matter of hours. It doesn't matter how recently it was cleaned, if something gets dislodged from inside the tank or the inner wall of a fuel line and gets through the filter, it's liable to get caught in a jet. It could be as simple as turning a screw, but I don't know what you have to give you any details.
Thanks for the response
I have a single cylinder 9 hp Vanguard Model 185432. I dissassembled the carburetor again today and can find nothing wrong with it. It's a pretty simple carb with one large jet, since ther is no low speed idle. I also tested the oil gard module and the off switch by disconnecting. This generator does not have the electromagnetic idle down.
Thanks again for oyur help

Is there any other info than just the rough idle? Does it throttle up smoothly? Any smoke during any operating condition? Color of the smoke if any? (thinking it might be puffing a little black smoke at idle and throttleup). Have you tried a new spark plug?

How badly does it run at idle? Is it just a sputter and miss or a surge up and down, or backfiring, etc...?

Is there any other info than just the rough idle? Does it throttle up smoothly? Any smoke during any operating condition? Color of the smoke if any? (thinking it might be puffing a little black smoke at idle and throttleup). Have you tried a new spark plug?

How badly does it run at idle? Is it just a sputter and miss or a surge up and down, or backfiring, etc...?

Does it throttle up smoothly? Yes

Any smoke during any operating condition? No

The generator is well maintained and has about 200 hours on it.
I've also replaced the air cleaner spark plug and cleaned the crankcase vent in the valve cover.

There is no backfiring it just runs rough causing the govenor to move slightly and the rpms to vary, as though it has a very regular miss that starts imediately after idle speed is reached.

That is governor hunting. It is generally caused by a carburetor restriction.

That is governor hunting. It is generally caused by a carburetor restriction.

O.K.
It's a Mikuni, about a hundred bucks to replace.
Do those things come set up and ready to go?
I've got it about as clean as going to get.
I like that B12 Chemtool as a carb cleaner.

I agree with cheese as it does sound like a carburetor issue. If you purchase a new carburetor it should pretty much be a bolt on proposition. You may need to reset the governor, and I would do that anyway, since you have had your carburetor off.

Have you checked your valve lash to see if they are within specs?

Could be time to adjust if it's never been done.

No I did'nt bother to check it, I figured it was O.K..
Do you happen to know what the specification is? Or where I can get that info.
Thanks for your help.

This Briggs check chart and much more info is available at the Briggs website. This should have the specs for your engine.

http://www4.briggsandstratton.com/miscpdfs/RNT/Engine%20Specifications%20Chart_ms3992.pdf

Best of Luck.... :thumbup:

My 5000 watt generator that I have had for ten years has decided to idle rough, This occured suddenly after the machine idled back when the electrcal load decreased. A prilimary inspection revealed the govenor spring was broken. I replaced this spring and the machine still idles rough. I think this broken spring was a symtom, not the problem:wall:


Not to disrupt the flow of diagnosis here but, is the replacement spring the correct part?
Could it be just a governor, or spring tension adjustment?

Not to disrupt the flow of diagnosis here but, is the replacement spring the correct part?
Could it be just a governor, or spring tension adjustment?

Not sure exactly what your asking...I apreciate your input, but let me try to answer.
The spring that broke was original. I replaced it with the oem replacement. Briggs and Stratton referred to it as the "govenor spring". It's purpose ( as far as I can tell) was to keep tension on the govenor linkage, what ever movement the bushing allowed would be negated. The linkage ran through the the center of the coil on the spring.
Thanks again

That is governor hunting. It is generally caused by a carburetor restriction.


You were exactly right! I replaced the carburetor Friday and used the generator all week end and it performed flawlessly. It just runs great. Thanks to you and everyone else that helped with good advice and Indypower for checking the part numbers. Saved me a lot of time and money because i did it myself:D.
Thanks again
RB

Great! Glad we could help and thanks for the update!