Small Engines (Lawn Mowers, etc.): Tractor hard to start, john deere tractor, fuel flow

Question
Hi Michael,
I have a 400 John Deere tractor. It is hard to start. When I turn the key, engine turns very strong, just won't start. I smell the gas smell after trying several times. Sometime just make an explosion sound. I could not make the 1st start this spring.
Please advise.
Thanks,
Jian

Answer
Hi Jian,

You will need to determine if the problem is a lack of spark or a lack of fuel flow.  Remove the spark plug, reconnect the wire and lay it against the engine head.  Pull the engine over and watch for good hot spark at the plug's electrode.

If good, then try to start it while squirting fuel or starting fluid into the carb intake.  If it starts and you can keep it running by adding fuel, then the carb most likely has dirt, debris or gummed fuel inside.
You will need to remove the carb, disassemble it, clean all the small internal openings and blow it out with compressed air.   Probe each and every hole with a small wire.   A carb rebuild kit wouldn't hurt either.  

Let me know how you make out.
Michael