Small Engines (Lawn Mowers, etc.): B&S powered Sears mower wont start, pldm, throttle plate

Question
Eric,

Thanks for your prompt reply.  I couldn't write back immediately because the service said your box was full.

My email address is se0001@gmail.com

This is the mower

http://www3.sears.com/imaging/ImagePageJava.shtml?productTypeID=1500600&brandID=

(you may need to scroll down to see it after it loads.)

I know the history.  It start and runs just fine if you manually hold open the throttle plate in the carb.  The carb is clean and tank is full of fresh fuel.

There is no engine speed control on this model and I can not figure out what causes the carb to open and close.  I have cleaned any accumulated dirt and gunk from all moving parts.

I have the feeling that part # 227 (on page 5 in the Briggs 120000 IPL) has something to do with the issue.  I think this is what you referred to as the "governor arm."  It moves easily by hand but doesn't appear to move on its own as part of a system of other movements.

I own another mower with the same style B&S engine but that mower has an engine speed control on the mower's handle.  With that one I can see how moving it adjusts the carb opening.  The reason I'd like to use this inherited mower is because it can mulch without a bag, which will help greatly with the amount of leaves we have in our yard.

Basically, I don't understand how the engine knows to open or close the carb without a throttle speed control cable?


Thanks,
Brian




Also, in the IPL below part #227 is part 616 (698801, crank-governor).  I don't see where this part is on the engine or understand what it is supposed to do.



Since you don't know about the mower history, I would remove the fuel tank and top engine shroud.  This engine model collects dirt/debris in the rear corner by the governor arm.  Removing the shroud exposes this area so you can clean it.

Since you have the engine apart, remove the carburetor and check the operation of the throttle butterfly by moving it by hand.  I would also remove the carburetor bowl and inspect the float bowl for debris.

Clean the areas and reassemble.
Let me know what you find.
Eric

-------------------------
Followup To
Question -
I inherited a Craftsman mower with a B&S 6hp engine (12h802-2675e1).
It is about 6 years old and will start and run if you manually hold the carb open while pulling the cord to start.  The cable attached to the lever on the mower's handle runs down to the left side of the mower and will move a pivoting lever but does not do anything to open/close the carb, which is on the other side of the engine.

I can not figure out what switch/lever/device is borken or missing that would open and close the carb.
There is no throttle speed control on this model.
http://www.epinions.com/content_171004956292

Thanks!
Answer -
http://shop.briggsandstratton.com/BShopProductPage.asp?CatalogID=56B2B9A7-283C-1

You can view the IPL at Briggs' website.
Since you don't know about the mower history, I would remove the fuel tank and top engine shroud.  This engine model collects dirt/debris in the rear corner by the governor arm.  Removing the shroud exposes this area so you can clean it.

Since you have the engine apart, remove the carburetor and check the operation of the throttle butterfly by moving it by hand.  I would also remove the carburetor bowl and inspect the float bowl for debris.

Clean the areas and reassemble.
Let me know what you find.
Eric

Answer
Fixed speed models are quite common these days.  Most of the fixed speed models maintain speed control by simply placing the throttle to high speed and bending the assembly to hold the throttle control in position.

So you have the governor arm, governor rod connected to the carb butterfly and then the governor spring connected to the round eye in the governor arm and the other end of the spring connected to the throttle control.

Do you have these parts connected?
Let me know.
Eric