Lawn tractor issues

I have an older John Deere lawn tractor K series 14hp that won’t start. I have fuel pressure and spark. I had it running yesterday but the rpms were low and wouldn’t run under load. Any thoughts 

How long since it ran?  Sounds like a gummy jet.

Bad gas?  Mouse nest in the exhaust pipe?

I put a new carb on it thinking it was gumbed up. The gas is fresh 

Governor spring fall off or broken?

Fouled up plug?

I've heard faulty gas caps could prevent starting.  Also, parking brake switch or seat safety kill switch.  A few weeks ago, mine starting bogging down about every 20 seconds for a brief few seconds while mowing.  I ended finding out that the vent tube was clogged.  It runs from the carb down through a hole in the frame and hangs there.  I cleaned it and runs fine now.  Not sure if that could also prevent starting.

Is it turning over?  Turning over fast or barely turning over?  Gas flow good to the carb?  Good strong spark?  Muffler blocked?  If the muffler has rusted pieces inside it could be closed off  ( Broken baffle ) that could prevent it from starting.  

It’s turning fast like there’s no resistance 

Incircles019 said:

It’s turning fast like there’s no resistance 

That sounds like a lack of compression.  Probably wiped out a cam lobe.

Or maybe ventilated the block? Maybe broke the connecting rod?

What engine?

B&S Intek engines can have an issue w/ valve seat inserts loosening or popping out = no compression. 

Check the compression.   Is it a Kohler pr Kawasaki?   The KW engines have been known to shear the woodruff key.   It should have compression.  Watching a Youtube video a push mower showed 110 PSI.  If your motor has a low compression reading, it may be time to find a new motor.   Your results may vary.

Had an odd issue w/ my Kohler Command. Cranked like a champ, battery tested 12+ volts, good fuel, spark and compression. Started, ran and drove. While cutting though engine would lose power, chug and eventually stop. 

Assuming battery was good, running w/ electric PTO engaged the fuel cutoff solenoid (anti-backfire) read less than 7 volts and would starve the fuel bowl. Battery marginal, replaced battery w/ new and all was good again. 

I've also had the blocked gas cap vent and old fuel hose degrading from inside and restricting orifices among other loss of power and running issues. 

0.02

I cranked the engine over today seemed like it wanted to start. While cranking I took out the dipstick and up with oil shooting in the air. 

I’m thinking I have bad bad rings.

Thanks to everyone for your input 

Overhead valve engine? Pull the valve cover, inspect.  Then crank and verify valves and springs are compressing as they should.

Indy-Barely Functional-Guy said:

Overhead valve engine? Pull the valve cover, inspect.  Then crank and verify valves and springs are compressing as they should.

and check/ adjust valve clearance