over revving and backfiring Tecumseh on Craftsman rear engine mower.

[erty67]

Hello. I'm having a tough battle with this mower and I'm hoping you guys can help. I picked up this Craftsman 30" rider recently that wasn't running. At the time of purchase, I could see the coil wire was chewed by a mouse, so I assumed it would be an easy fix. I was wrong. I replaced the coil and did get it to start, but only in choke mode. As soon as I move the lever off choke, it starts over revving like crazy and backfires. It's actually pretty scary. I was told it was probably the carb, so I bought a brand new replacement carb, but same problem. The motor is a 13.5HP OHV Tecumseh. Can anyone help me figure out what I'm not doing right? :smile:

 

[erty67]

the carb that's on it is a 640164, which is Sears' listed replacement. here's a ebay ad to show pics of the carb itself.

eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

 

[ILENGINE]

When you put the engine at the full throttle position when it is not running does the throttle move the medal tap that hits the screw toward or away from the screw. If it moves toward the screw then the linkage is backwards and need to be moved to the other hole in the throttle plate on top of the carb. If the connection is correct then the governor may need to be adjusted for the static position.

 

[erty67]

It's on the outer hole, so it turns counter clockwise opening the plate inside. when it does surge, the governor rod pull it full open, causing it to rev like crazy. It just goes full max rev when I open the choke.

 

[KennyV]

Like ILENGINE pointed out... a over revving problem is going to be the governor or the linkage...
There should be a spring pulling the throttle to wide open, and the linkage from the governor is going to try to close the throttle...
check if the governor is working at all... don't let it run away with itself, it can come apart if it gets winged up too high.... :smile:KennyV