Why won't my riding mower start?

Question

Mower (an old John Deere S82) intermittedly turns off and was difficult to start. After cleaning the filter and fuel lines, the mower does not start. The spark plug is new and the spark tests okay.

Answer 1

Pull the carburetor off and check to see if the last batch of gas has turned to shellac in the jets. I suspect you loosened something and plugged it up. Othe than theat check the spark.

Answer 2

Be sure you check the spark with the plug attached to the plug-wire, I recently had a cracked insulator that was difficult to see, and the spark was jumping to ground deep inside the plug.

Beyond that, you need fuel and compression. If you can see into the carburetor you may be able to toss a 1/2 teaspoon of gasoline into the throat while cranking - if that makes the engine fire for a second, the problem is fuel-related.

Perhaps something was dislodged during the fuel line/filter work and clogged the carburetor.

As for compression, if you don't have a compression tester, you can usually tell if the engine has compression by the sound it makes while cranking - if it's smooth and doesn't sound like the starter motor is speeding up and slowing down, there might be a problem with a valve sticking open.

Answer 3

It only takes four components for an engine to run.
1. Air
2. Fuel
3. Compression
4. Spark
The air we presume it is getting.
The spark from your description is there.
That only leaves 2 components to be considered, compression and fuel. Try to turn the flywheel by hand, if it turns freely then stops you should have compression. That only leaves fuel as the lone culpret keeping your engine from running. Cleaning the filter and fuel line is only a small part of the system. Clean the carb inside and out, since it is an older engine a rebuild kit will probably be needed.
Hope this helps!

Answer 4

Unless its one of those cleanable type filters, throw it out n get a decent one, its cheep insurance that your tractor will run everytime. Dont bother with the screen types, it only filters large debris. Does this motor use a fuel pump ( vaccum operated)? Check and see if the line from the motor isnt plugged ( vacuum line) - its possible some gunk is in there, my father mows his neighbors yard with a 4 year old Cub Cadet , he maintains it routinely, one day it wouldnt start. We went thru the routine, and saw no gas was comming in. On this Cub, the vacuum line is from the valve cover- turns out some oil got into it and plugged it, we cleaned it out- it fired right up. Could it be a saftey switch gone bad?
Kidd

Answer 5

When you say you cleaned the filter, did you mean air filter? When an air filter is old or cleaned and not changed it will keep the engine from getting clean air and no air to the engine will keep it from firing and starting or bogging down and shutting off when the engine heats up. Check air filter, check the spark plug for fire, check fuel for foreign substance such as water or oil.

Answer 6

Silly question, but do you have it in neutral. Check all the wiring harnesses. And how about the battery. Mine started to stall all of a sudden, and it was the spark plug--the little screw on tip was loose. Could something have happened to the seat "dead man" thing that automatically turns off the engine when it can't sense pressure on the seat.

Answer 7

Due to your cleaning, you have left the fuel lines empty. Unscrew the spark plug and squirt one medicine dropper of fresh gasoline into the cylinder. Replace the plug and wire and start it up. You may have to do that a couple of times, but it should start.

Answer 8

I am not agree with Papaw answer...! You are here to assist folks with answers not to tell them to go and spend money with the money hungry techs....! Look for a 25 amps fuse located on the hot wire to the battery usually behind the seat. Other tips to look are deck and steering sensors out of adjustment and not making contact. Cub Cadet must have also a sensor on the manual brake handle. Also have a safety switch under the seat. I hope these tips will do for you, otherwise you must take that lawn mower to one of those money hungry lawn equipment techs like Papaw said...! Good luck....!

Answer 9

You said it's old and that makes me think of compression. If the cylinders are tight to the block and the heads are tight to the cylinders (gaskets included), your rings might be worn. Check to see if you're getting any gasoline in the oil from blow-by. You might want to make sure the 'dead-man' switch under the seat hasn't been moved or see if it is working at all.

Answer 10

I had a similar problem when the kill switch came out of its bracket. You may need a second person to watch under the cowling as you press down on the brake.