Briggs Auto Choke Problems

[Joe Struthers]

Good morning, I have a three year old "Brute" lawn mower with a Briggs and Stratton 725ex series motor (190 cc / 7.25 gross torque). I was preparing for the new season by cleaning carb, new plug and air filter. I removed the muffler not knowing that there was an auto choke solenoid tucked behind it. Reassembled but suspect that I may have done that wrong because engine now runs VERY rough for about two minutes after cold start then picks up and runs well after that.
Question - is there a special way to connect the vertical choke solenoid arm to the wire which (presumably) runs to the carburetor? Alternatively can any one suggest a fix to my problem? Need help soon - grass is growing fast! Thanks

 

[pugaltitude]

http://www.lawnmowerforum.com/toro-wheelhorse-forum/24253-toro-recycler-will-not-start.html

Have a read.
If its also running rough then more likely carb needs a good
clean.

 

[Rivets]

Look at the picture in post #15 of the thread pug gave you. I'll bet that will be your problem area.

 

[vogtrj]

Is the choke solenoid you're talking about the thermostat? If so, the air vane does not go through it. It looks like it does but the air vane should swing free on that end outside of the thermostat.

 

[Joe Struthers]

Thanks for the responses. I will check the carb (again) and also have a look at the connection of the solenoid arm to the choke linkage. I appreciate your help. Joe

 

[Joe Struthers]

Good morning again from sunny Nova Scotia. Found the problem. When I had reassembled the thermostat mechanism (part # 790830) behind the muffler, I had assumed that the air vane (part# 790849)(which operates the choke) should be linked through the loop in the top of the vertical lever connected to thermostat. NOT SO! When assembling, the air vane should be behind the vertical thermostat lever (towards the operators end of the mower). The thermostat lever reduces choke as the engine heats up by allowing the spring loaded air vane to swing forward. The complicated looking end on the thermostat lever does not connect or hook onto the air vane. After I reassembled the thermostat and muffler, the mower started and ran very well after the first pull. So now I am cutting grass!
Thanks for your input - hope this thread will help the next the next guy who tries to mess with the muffler on his B&S without an instruction manual.
Cheers - Joe

 

[vogtrj]

Joe - In my few days working on these engines and reading this forum, it is clear that this is a very, very common mistake. Glad you're up and running again.