The machine is a Craftsman lawnmower with a Briggs and Stratton 190cc 675 series engine. This manual matches my paper copy.

I received the mower as a freebie recently and knew the previous owner had work done on it and was having problems. When I was trying it out, the engine would run poorly and then stop. I removed the air filter and could see the choke and see the mechanism that controls it. As the mower was running, the mechanism would move towards the green arrows, closing the choke. I would push back against the mechanism, forcing the choke to open up some, and the engine would come to life.

How should I go about fixing this properly? I only know of the two springs that I can see (I can see the one pulling on the choke mechanism running vertically in the image, and another to the right in the image, running horizontal, with unknown function). Neither spring seems deformed but they could easily be an incorrect spring.

 

I have a couple of those I will look at mine in AM. I thint the linkage with the u goes in the slot and its spring goes under the cover on the upper part of picture.

 

When the arm moves in the direction of the arrow, it opens the choke, not closing it. If it runs poorly with the choke open, then the carburetor needs to be cleaned out.

 

Okay, I see that the choke was closing, not opening, and have found a good visual guide for cleaning out the carb on this 190cc engine. I will be back when I get it done or get stuck, thank you.

 

I removed the float bowl and it looked okay. The area was clean and the float moved easily. Removing the carburetor itself was more than I wanted to do today, so I tried using a dozen shots of a carburetor spray with no effect, except that it ran for an extra two seconds as it burned up the spray.

I wanted to get in one more mowing before winter and with today being good weather and a risk of rain tomorrow, I wired-down a shim against the mechanism to prevent it from moving the choke to the fully open position (the shim was about 2/16 to 3/16 thick). It was working so I started mowing and got about 1000 feet done before it stopped. Some plastic was showing at the bottom of the gas tank so it might have been out of gas, but after adding more gas, it still continued to stall out immediately so I stopped trying, thinking it might be something else (the sun was dropping as well). After that 1000 feet, the shim was still in place and the spark plug was almost clean.

Is there anything I can introduce though the gas tank that will "melt out" the clogging over time? In the carb, I would see the tube that introduces the gas from the float tank, but couldn't get spray into it.

 

Take the bolt out that holds the float bowl on and clean the holes in it. There are 4. Make sure you clear out all 4, especially the tiny one up in the unthreaded section.

No, there is no mechanic in a bottle.

 

That was it. I put wire and spray through the holes in the screw and up into the carb's throat, removed the shim and it runs excellent now. Thank you.

 

Glad we could help, thanks for the update!