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JohnF2015, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1051
Experience:  Owner/Service Technician at S & J Small Engines
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I Purchased a 725 ex Snapper lawn mower last season at Walmart.

Customer Question

I Purchased a 725 ex Snapper lawn mower last season at Walmart. Used 1 season used gas treatment before putting up.
This season will not start. I have completely disassembled and rebuilt the rebuilt Carb. Replaced Spark plug, changed oil, took entire shielding of engine and and check Magneto contacts, wire and Blade control contacts all engage properly (Or at least appear to). All Ok. The springs all seem to be operating as designed.
Behind the muffler is a strange lever that has a self contained spring in it. It appears that it should push against a plastic arm that traverses the front of the Magneto. This armature seems to have some influence on the (or control of) the butterfly valve(s) in the carburetor. In this case the spring action on the lever mechanism is week and doesn't seem to be pushing up against the plastic arm , so I am curious if it is not opening a valve properly because it isn't engaging properly.. The only think I can think of is that it is designed to be heat sensitive and expanses as it heats, thus pushing the mechanism forward on the lever arm.
I have maintained several mowers over the years and was always successful in rebuilding and tuning up my mowers, until this one.
Any suggestions?
Submitted: 8 months ago.
Category: Small Engine
Expert:  JohnF2015 replied 8 months ago.
HI, my name is***** will be assisting you.The arm and spring mechanism is a thermostat of such, it is there to open and close the choke on the carburetor. If it is not working properly then the choke will not close which will cause you trouble with starting the engine, but it will also not open the choke as the engine runs and warms up in order to keep the engine running properly.You mentioned that you cleaned the carburetor. Did you clean the three small holes in the bolt/nut that holds the carburetor bowl on? If not you will want to do so as these small holes serve as the main jets for this carburetor. There are two holes parallel to one another in the sides of the bolt/nut and a third hole right down through the top center of the bolt/nut, just make certain that all three of these holes are clean and free of any obstruction.