The Tecumseh engine on my mower will not start. When I turn the key the engine will spin until it hits compression then stops. If I remove the spark plug the engine will spin just fine. Have new starter and battery. Anyone have an idea?

 

It would be helpful to have more details such as horsepower and mower type, at least but engine ID numbers are even more useful. But, based on your problem and assuming you have a fully charged, new battery I'd say you have a compression release mechanism at fault...that's if you have an engine with one. Or, possibly, the ignition is off time.

 

it is a Lawn General mower, made by Murray. The engine is a Tecumseh 17hp ohv Enduro xl/c.

 

This engine should certainly have an MCR camshaft and it could certainly have failed. The way to check (other than disassembling the engine) is to first set both valve clearances to specs and then remove the cylinder head in order to inspect for valve lift on the bottom most valve as the piston approaches TDC on the compression stroke. Absolute first though, I would not assume you purchased a fully charged battery or, for that matter, a good battery. Have the battery professionally checked for proper voltage and cranking amps. Even though your battery is new, it may have been on the shelf for a long period of time.

 

having trouble trying to find the valve spec. do you know where i can find it?

 

Start with the basics first:
Remove the spark plug and pour a small amount of gas down the hole..install plug and try to start again. If that doesn't work remove the spark plug and attach the wire and restart and observe the plug for spark.

 

Warstud, the problem is the engine won't even turn over, let alone crank enough to try to start it.

rtmcgill, I believe you'll find your valves are too loose. Set them both to .005" with the engine at TDC and I think you'll be going again.

 

reset the valves, they were not out very far. Got the battery fully charged and managed to get it started. tried it several times and it started ok. some hesitation when it hit compression. ran it approx.1 hour and shut it off. now it is doing the same thing. it isn't the battery though. now the engine stops spinning and the starter keeps going so it has to be something in the motor itself.

 

If the starter is spinning but the engine is not, it sounds like a starter problem, or a stripped spot on the ring gear of the flywheel.