Craftsman 10hp riding surges when under load


Old 08-09-04, 06:24 AM
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Question Craftsman 10hp riding surges when under load

I have a Craftsman riding mower(model 502 255094) with a 10 hp Techumseh motor with a bowl carburator. Bought the mower used so not sure if motor matches the body. No problems with the mower until recently the mower starts and idles ok, but when you engage the gears and blades and begin to mow, the motor's rpm surges(runs fast, then slow, fast, then sow,etc...) A friend suggested it may be a govenor problem but I need help diagnosing.
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Old 08-09-04, 09:44 AM
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Sounds like it could be as simple as a carb adjustment. I think your carb only has one mixture screw, should be right above the bowl with a spring on it. Count how many turns out it is now by turning it CW until it lightly seats, (note the turns) back it out CCW 1 1/2 to 1 3/4 turns to begin with. Start the engine then slowly back it out (CCW) until you hear the engine begin to stumble a bit then turn it in 1/4 turn. If this doesnt help or the screw has no effect the carb may need a good cleaning. Unless the govenor has been messed with, its not likely to be the problem.
Old 08-09-04, 02:42 PM
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If this is the original engine, it will have a Tecumseh engine, model # TVXL220, serial # 157245B (the tag on the engine will read - 143.426072). The carburetor on this engine has two adjustments. The main (directly under the bowl of the carb) and the idle circuit. The main will be adjusted to 1 1/2 - 1 3/4 turns out from bottomed and the idle will be adjusted to 1 - 1 1/4 turns out. Try this first and if it doesn't solve your trouble, post back and I'll walk you through a governor adjustment. Let us know.
Old 08-09-04, 06:45 PM
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Easy fix with good advice, thanks! The idle adjustmant settled on 1 1/2 turns CCW but for some reason the main adjustment ended up being at 3/4 turn CCW instead of 1 1/2 to 1 3/4. I ended up with this by running it under a load and adjusting the main while driving. Is this difference due to wear or age? Also, is there a trick to getting the correct adjusment when under a load? Regardless, thanks for the good advice and a simple fix! Now, for another problem, while testing this repair, my mower deck began to make a lot of clanging noises. On first inspection it looks like the main(the one over the blade and the largest)pulley wheel may have broken, it seems to have a lot of play around the shaft and slides up on the bolt. Where can i get a good diagram of the deck assembly to help me diagnose this new problem. Regardless, thanks again.
Old 08-09-04, 07:30 PM
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A sound cleaning of the carb should bring the adjustments back. Apparently you have some restriction in the passages of the carb. Dirt debris, build up.....

For the deck assy follow this link and have your model# rdy

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