# St/12 will not stay running



## BRay09 (Jun 11, 2017)

Hi all new here. Brought my grandpa's st/12 back from the dead.

Craftsman engine model number: 143 622102.

Been sitting for 10+ years. My zero turn took a crap and i don't have the money to buy another at the moment so i figured I'd try and get it running to use it for the time being. Removed carb and cleaned rust/corrosion and removed jets and cleaned them. Removed gas tank and cleaned due to rust. Put everything together and it fired right up. Changed engine oil and spark plug. Have used it to cut my 3 acres for the last 2 months. 

Until last week... Noticed smoking coming from the belt. Found the clutch pully failed. Found a replacement at tractor supply. Fixed that and put a new belt on the actual deck and drive belt. Now it won't stay running. It'll start for a few seconds at full throttle with choke out n then it'll die off again. Removed carb and fuel filter. Went through carb again and replaced filter. No change. Fuel is getting to engine, the thing just won't stay running. Any ideas on where to go from here?

Thank you,

Bill


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## sixbales (May 18, 2011)

Is the replacement pulley you found an exact replacement? Are the replacement belts exact replacements? My first suspicion is that you have a slight belt load on the engine and it cannot get up and running. I would remove the belts from the engine pulley and see if the engine runs.


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## bbirder (Feb 26, 2006)

sixbales said:


> Is the replacement pulley you found an exact replacement? Are the replacement belts exact replacements? My first suspicion is that you have a slight belt load on the engine and it cannot get up and running. I would remove the belts from the engine pulley and see if the engine runs.


+1

If engine still does not run with belts removed, it sounds like a fuel problem. Check float for leaks and or adjustment. It must be starving for fuel until the choke sucks some in. Could be you still have some rust particles floating around in there.


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## FredM (Nov 18, 2015)

does the engine run while the deck is disconnected or is as you write "It'll start for a few seconds at full throttle with choke out n then it'll die off again", just reading between the lines from what you have written, I would check all the deck spindles, idler pulleys for a seized bearing,, if the bearings are ok, I would next check the ignition module, the ignition can give you the same problems as fuel, nobody seems to correlate the two as problematic with much the same problems being presented.

although most likely not a cause, you may have a faulty sensor in the system.

seeing that the mower sat for so long and you have cleaned the fuel system twice, I would test the ignition module.


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