When your Tecumseh engine will not start, but it has spark, gas and a clean air filter, then you will need to check the compression. A compression test that shows air pressure under 10 psi (pounds per square inch) indicates that the piston rings are worn out, or the head gasket is worn out. Replacing the cylinder head gasket only takes a few tools and can be done in your own garage.
Things You'll Need
Socket set and socket ratchet
Foot-pound Torque wrench
Pull the spark plug cap off the spark plug on the front of the Tecumseh engine.
Unscrew the eight bolts holding the cylinder head on the front of the Tecumseh engine, using the appropriate socket, usually 9/16 inch.
Pull the cylinder head off to expose the top of the piston and the head gasket stuck to the back of the cylinder head.
Peel off the head gasket and place the new one on the cylinder head.
Place the cylinder head back on the engine block with the new head gasket in place.
Finger-tighten the bolts through the cylinder head and into the engine block.
Fit the socket you used to unscrew the cylinder head bolts on the foot-pound torque wrench.
Finish tightening the cylinder head bolts with the foot-pound torque wrench. Tighten one bolt to 165 ft.-lbs. (watch the meter on the foot-pound wrench handle.) Then tighten the bolt on the opposite side of the cylinder head. Continue to tighten all of the opposite-side bolts until you have all the bolts tight. By tightening the bolts on alternating sides of the cylinder head, you will properly seal the head gasket in place.