I never put one on a tractor, but I put several on gas engines to equipment I let set to long with fuel in them. The first one was on my old snow blower. I pulled the bowel off and it was a solid mas of yellow gel. The china carb was cheaper than a name brand rebuild kit. I was impressed. All I did was bolt it on and hook up the linkage. One or two pulls and it fired right up. All the adjustments were perfect. Then I put one on a Troy Built tiller and a gas power washer, just bolt and go, no problems. I have also heard horror stories.