Governor jumping around like crazy

On a John Deere D110 with a B&S engine 33R8 77 0004 G1 it started a couple of weeks ago the engine surges forth and back at all rpms but when I hold the throttle steady the engine runs just fine. The minute I let go the governor starts going forth and back and everything goes crazy. The engine misfires and I can see the throttle linkage going forth and back trying to find its sweet spot but can't for some reason. If I assist the throttle manually the engine runs like a dream. Help!!!

SRT, where are you????
 
I did some more testing. I disconnected the governor completely from the throttle linkage to test the governor without having to get into the sump. I started the engine and manipulated the throttle manually with one hand and had my other hand on the governor lever. As I went up and down on the rpms the governor responded accordingly, smoothly and the lever went forth and back indicating to me that the internal mechanics are functioning properly. Looks like I don't need to open the crank case. But I found out something else. I was only partially right when I said that the engine was running like a dream. That was only in the higher rpms. Now I discovered that the engine always wanted to stall in the lower rpms. Now I suspect that there might be a problem with the carb after all. It's on my bench right now. Hence the question about the solenoid. Also in normal running operation is the solenoid energized or not. What is its function? My gut feeling tells me that the governor and its related parts, springs etc. are not the problem. I suspect the carb, I ordered a new one for the hell of it. It's only 15 bucks. If that doesn't fix it, back to the think tank. SRT I miss your input!!!

Thanks, Mike. So with other words the solenoid is always energized when the engine is running. One more question. What is holding the main jet in its place when the solenoid is energized?

Sorry, I didn't get any notifications of new posts...
 
As Mike said, the solenoid, when activated with 12 volts (crank/run) opens and allows fuel to flow.
 
Here is your engine's parts diagram:
https://jackssmallengines.com/jacks-parts-lookup/manufacturer/briggs-stratton/briggs-stratton-engine/200000-399999-series/33r800-to-33r899/33r877-0004-g1 
 
As Mike said, the main jet can screw in or be "set" in place.
There's 2 carbs available for you engine.  The Ruixing or the NIKKI (see diagram on above link).
 
The solenoid just screws into the bottom of the float bowl.  If they sit a long time, they can get stuck 
in the closed/extended position.  If any doubt, I remove the solenoid and cut off the pin that extends(and stops fuel) from flowing..   The solenoid now doesn't need power/can't go bad as you 
removed the pin...  As long as the carb float/needle are properly working, it won't hurt anything.
 
The Ruixing is the basic/ built like most carbs.  
 
The NIKKI, IME, is junk.  The large plastic part that holds the float/needle/jet (jet is stuck right down the middle) uses a funky "gasket".  Some NIKKIs have a separate o -ring that goes bad, leaks or just doesn't seal...  
 
Did you re-set the governor with the carb?
 
.
 
Scott

 

That's great!!
 
I've never come across that specific cause/issue... 
 
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