B&S engine revves out of control

hi. i have a B&S engine model 12E114-0268-E1 on a craftsman model 536.881800 snow blower. it has been performing quite well for the past 8 years or so. but when i went to start it up just recently, it immediately revved up at really high rpms, forcing me to quickly shut it down. all subsequent starting attempts resulted in the same thing. i have used this snow blower many times for years, and have never experienced anything like this, or any other unusual behavior for that matter. a closer inspection revealed that the circular-shaped valve throttle (part no. 691181) inside the carburetor is always wide open, leading to a tentative conclusion that a governor is to blame. so i went ahead and removed the gas tank to get to the governor lever and spring setup. i have enclosed two images depicting the assembly. right away i noticed that a second spring should perhaps reside between a hole marked A and a hook marked B, especially since hook B looks identical to hook C that already bears its own spring. however, the manual only mentions a single spring (part no. 692571). so what i need to know is whether or not this particular engine model does, in fact, contain two springs in its governor lever setup. and if it is a single spring setup, what is the purpose behind the aforementioned hole A and hook B that seem to be begging for a spring? thank you for your time!!!

 

Make sure the throttle valve in the carb is not stuck. It should move freely by hand. As should the governor arm and linkage to the throttle valve.

 

Hello Brock_Samson,

They are there for a smaller spring which would be called a Governed Idle Spring, Some equipment manufacturers require their machines to have a governed idle speed and some do not. It would be too costly and a waste to build the same parts without a hole or tab so their built with, Then the spring is added on the assembly line per the the equipment manufacturers request.

If your engine doesn't have this spring and it's not shown/listed on the same page you got the part number for the high speed governor spring per your engine numbers, It's not supposed to have one.

I concur with BFHFixit on the stuck carb throttle shaft, It's common for them to get gummed up from sitting due to fuel sitting in the throat. The use of carb & choke spray cleaner will dilute the gum and free the shaft.


Good Luck

 

thank you for your replies. yes, all mentioned parts move smoothly. which leads me to a follow-up. how difficult and costly would it be repair the actual governor, or at least to get to it for inspection purposes? is there perhaps some online guide with big bright pictures that breaks it down into simple steps? if there is no such site, which repair manual would you recommend?

 

I would suggest adjusting the governor first before tearing into it if everything is moving freely, I would also take the carb off and make sure the throttle plate is still tight on the throttle shaft. I've seen the screws back out and cause the plate to stay fully open.....





Good Luck

 

thank you for providing such detailed step description. i will be sure to perform the procedure as suggest. before i do, however, i have some quick questions just to make sure.

1) steps 1 and 4 refer to a governor crank, while step 3 refers to a governor shaft. would i be correct to assume that they are the same thing?

2) when loosening the governor arm in step 1, should be to the point where the arm moves completely free?

3) what is the special tool in step 3? the picture seems to show a flathead screwdriver.

 

Brock,

1) Yes, They are one in the same..... Don't know why it's written like that.

2) No, Not completely free..... Just enough to twist the shaft in the arm.

3) Some use a screwdriver, Some a torx socket, Some a small hex socket, Just use whatever it takes to rotate the shaft while holding the arm with the throttle shaft in the wide open position.


Good Luck