mower issues

bought a new john deere mower 4 years ago ... seems like a good mower ...

this year it is acting stupid ... if i fire it up and run for 20 min or so ... it is great ... but the moment i shut it down ,,, if i do not fire it back up in 30 sec it will not fire up for an hour ...

it is a 17.5 hp briggs engine i have stayed up on the oil filter and plug changes like clockwork .... but i have no idea what is going on ???


it is not flooding out .. checked that ... oils does not smell like gas ... .. pumping fuel ... ....

if i fire and run he entire yard ,,, no trouble ,,,, shut down to do anything it is 45/60 min wait till it will fire up again


magneto getting hot ? or another issue ????

 

Could be the ignition module getting hot...have you blown out the debris from under the engine shroud recently? Grass clippings will fill it up and not allow cooling air to circulate...

 

Vapor locked from overheating. Clean out the air passages.

 

cranks but will not fire ...

 

Getting spark after it's hot? I suspect the mag might be letting go! Check your ignition switch for corrosion and check your grounds as well!

 

Check your plug as soon as you shut it down.

Take a picture of the plug and post.

The 10 % or more Fuel tends to cause problems.

 

LOL it sound like the perfect mower for a procrastinator. Start mowing, decide this stuff is a pain in the butt, make a valid excuse to stop, any valid excuse. Stop, and low and behold, it will not restart. No problem, go enjoy a cold beer and watch TV, maybe have a snack. Damn the AC feels good and I am a little drowsy, seem like a good time for a nap, I'll see if I can get the lawn mower to work properly tomorrow. If the wife doesn't believe any of this, get her on the mower to prove it. Let her stop by calling her to stop for any excuse you can think of. Then jump on the mower, and of course, it won't start. Have her verify it won't start. I rest my case.

 

Hey.....I resemble those remarks......

OP: I'd say vapor lock as well. Ignition problems wouldn't go away in a hour.

 

Well, if there wasn't a pile of hay insulating it, they might clear up rather faster than an hour. Dunno. I keep my airways clear, and my Deere does collect "hay."

For the sake of curiosity, how many hours are on it? Are you keeping up with the maintenance schedule?

 

Most likely heat shield or grass clogging air for cooling, as long as it runs you have air flow and it stays somewhat cool, shut it off and heat conducts to carb or ignition mod and it over heats until the whole engine cools down again. Carb or ignition may be marginal so if you find out which is bad, replacing it might help, but still need heat shields and cooling. Have seen it happen in a good carb when that wired looking big piece of thick paper gasket wasn't placed between carb and intake manifold as a heat shield, or sometimes it is a thick piece of plastic. Worst one I ran into was an air leak in the intake manifold that was made worse when the manifold warped when it got hot and allowed air to make mixture lean. When you shut it off, wouldn't start, choke just pulled more air thru leak, when it cooled, it straightened out enough to start again and at open throttle, little air was sucked in and it ran.

 

"The 10 % or more Fuel tends to cause problems."
1.10% Fuel provides less energy and the engine works harder, gets hot, burns tips of plugs and burns valves.
2. Once hot the parts expand and cause the mower to try and start in a lean condition.
3 . Engine cools down over night and starts.

 

I like the @HK_User theory
about fuel. Lots of shaking/mixing going on with the engine running.
*Insert appropriate safety warnings here.

So while you crank the engine, hold a gas soaked rag over the air filter. If it starts it sounds like a fuel problem. No start could be an ignition issue.

 

A quick way to check for vapor lock: After you shut it down, put a box fan on it to cool everything off. Then try it about five minutes later.

If it fires right up, you've found the problem.

 

BOX Fan as in 120 volt house fan?

I only ask because when I hear Box Fan I think of a computer and its Box Fan!

 

Any fan.
Ignition modules are frail and prone to fail due to heat so keeping the cooling system free of cuttings is critical.
If the fuel line is run past the cooling fins of the engine vapor lock is another possibility I have rerouted in some cases ,
Another possibility especially if all else is been done is the valves . Notoriously the valves wear and the clearance to the tappet disappears and as the engine gets hot the valves grow in length , so while every thing is running it's just fine but once off the length of the hot exhaust valve is rendered it basically open, removing compression for starting .Once it cools off and shrinks to normal compression can be achieved . Of course eventually valve seat wear and this clearance will render it with no clearance at all and not run no matter what .
Clearance on practically all Briggs engines is .007 intake -.011 exhaust .

 

Sounds like it's blowed up!!! I'll give you $27.92 for it as it sits!

 

You can have mine for that.

No delivery you pick up on the 5th Monday of next month.

 

Thats why I buy Honda no issues for years so I bought another one

 

That's July 29...you did pick a month with 5 Mondays

 

Yup but he doesn't have the address.