Hope you experts out there can give me some clues before I become desperate and turn to a pro. Here is some info about the tractor and what I have done so far:

This is a 1999 Kohler electric start 42' mower, bought new in 2001, model 917.271141. I have replaced oil filter, air filter/screen, fuel filter, and spark plug. It does start with choke, but dies instantly once release the key or shift to full throttle. Inside carb, choke & throttle adjustments seem to work just fine, and sparks look OK but a little suspicious, since no sparks at all as soon as key is released. Also, while inspecting sparks with plug out, don't see any fuel mixture puffing. However, when I try to start again, always get backfires with a bang (thought indicating no fuel line issue). Inspected all three switches (seat, engage and brake), they seem to function as supposed to (but not sure if any electrical fault). The gaskets between the carb and engine are fairly worn and a little dirty and will be replaced. After all above, with fresh fuel, still no luck. The very last time it started with some difficulty (after a few tries) and when I engaged the mower, it died.

I'm a total novice, never opened an engine and not even sure how the fuel is pumped (don't seem to have a pump, but don't fully understand my carb either). Short of opening up the engine, is there anything simple that I can do before turn over to a pro? Could it be gum caused valve sticking? Help!

- ny4fun

Could be the ignition switch since you stated it quit firing when the key was released, could be the flywheel key if it is backfiring as you say. Check the flywheel key by removing the blower housing (top of engine) and the nut that holds the flywheel down, visually inspect, you should see a groove in the flywheel and the crankshaft, they are to be lined up.

The flywheel key shears to protect the engine under extreme stress.

Umm, yes that is right k.i.s.s. (what a name).

So do propeller keys. You learn the hard way when you have to row back to shore. <G>.

Row , row , rrrrrrrrrrrrrooooooooooooowwwwwwwwwwwww your boat kiss.(do you mean that mean like? some people may see it that way, [keepitsimplestupid].

Thanks guys! I'll take a look at the flywheel key. This may be a little challenging to me with limited tools and experience, but I'll let you guys know. If it is not the problem, I'll replace the ignition switch.

I don't quite understand why no fuel puffing out from the plug hole when I tested it several times, and yet if I try twice or more on choke, I get the bang. The owner's manual is almost useless to a novice like me. Any suggestion for a better manual?

There are shop manuals available, although may be a little hard for you to come by. Use extra caution when replacing the switch. Some shops will carry aftermarket switches, if you look on the connections, or the body of the switch by where the connections are, there will be letters designating what that connection goes to. If these are not in the exact correct order, your mower is going to either fry something electrical, or just will not work.

MM:

No I don't mean that mean. I was young, like maybe 12 or younger and was out on the water with my uncle on Lake Michigan on a row boat with like a 5 HP outboard motor. I think I was "piloting" and hit something with the prop. There were no extra sheer pins in the boat, so "row row row your boat" so to speak back to shore. You learn the hard way what it means to "be prepared".

KISS

MM, k.i.s.s.

Following your suggestion, I took off the blower housing and the nut holding down the flywheel, but unable to take it off. Tried gently to prod it up with screw driver and wedge , but didn't work. Any special tool or trick for this?
Of course, I don't want to damage anything, and boy, taking out the nut was some challenge with self made tools.

Well, with the nut removed from the flywheel you should be able to see if the key is sheared or not. If it is not aligned up it is sheared. Sometimes this is difficult to remove (the flywheel) even with a flywheel puller.

Hey MM,
A blue mark on the shaft and the slit on the flywheel are not aligned, about 90 degrees apart. I suppose the key is under the flywheel and is damaged and ought to be replaced. I guess even the key is not damaged and just needs to be realigned, I'd still need to remove the flywheel first. Hold on, I'll let you know.

The key is damaged.

It's visible when you remove the nut like MOWERMAN said.

Pulling the flywheel is a different story all together. It fits on a cone, so there is a lot of surface area that can grab. A flywheel puller may be required.

Thanks kiss!
I've tried various ways and still can't remove the flywheel. Tried to pry it up, rock it loose, and lift it up by securing a long metal rod to the flywheel with the fan securing screws and nylon wires. Doing so, I almost lifted the tractor many times and yet the flywheel didn't budge. Need to hit a tool store for a puller before retry.
This is my first attempt ever to play a mechanic, and with your help, it's fun and hope to get the tractor back to life without the help of a Pro.

You need to be cautious, you are scaring me now. Remember you are working with aluminum crankcase. You pry too hard and you need an engine housing, and I don't think you are up to that. You can get a flywheel puller for a briggs and stratton engine. Apply the nut flush at the top of the crankshaft bolt, apply the puller, set lock nuts against bolt threads going into the flywheel, tighten the nuts against the puller itself, then give it an EASY blow with a hammer. Then tighten the top nuts against the puller itself and tap again with the hammer, not TOO hard though. Remember you are dealing with your crankshaft here. Be careful.

Look at page 12.

http://www.briggsandstratton.com/mis...T/tool_cat.pdf

You have to get one for your engine. You can get a diagram of your engine on this site so you can see what your up against.

MM,
Thanks for your warning! I was quite careful and easy on the flywheel, not wanting to cause any further damage to the tractor for sure. I'll get a puller and do what you prescribed and wish me luck.

KISS,
Thanks for the link! The basic tool set is already an eye opener to me. I barely have any of these tools. No wonder I was wondering how am I supposed to get the right torque specified, etc. I definitely need a few pieces of them to get the flywheel work done right.

I remember designing and building something and I kept having to make special tools in order for the design to be workable.
1. A tool to square a round hole in teflon
2. A split nut to hold a set screw in a lathe so I could drill and tap it without
Damaging the threads
3. A spring depressor, so I could insert a pin

And then tricks to add a 0.002" gap so Sn 96 solder would flow between two very small flat pieces 1/8" wide and 0.4" long x 1/16" thick and a piece of 1/8" square tubng.

Any progress? Remember , be careful!

Didn't find the right puller yet, but with help from a friend, tried a lot more diagnosis. First, did see the key in the slit on the flywheel (could it really split off from the keyway from shearing?). Second, taking spark plug out, turning flywheel around confirmed piston reaches top when magnet hits coil, seems to suggest flywheel key still in place. Third, spraying start fluid and WD-40 into carb many times, didn't start. Forth, further confirmed strong sparks. On choke, it almost starts normal until switched to run or backfires if I hold at ignition for too long.

Will get a puller in the next day or two to take off the flywheel, and then thinking about taking off the cylinder head to inspect valves. I was ignorant and didn't empty fuel tank for the past 6 winters, and didn't use stabilizer either. Spraying into carb didn't start, seems to suggest either fuel cut off by non-responsive intake valve? Also, before it died, I do recall I had less and less reaction time to move to full throttle after start at choke, not exactly sure what this suggests. I would've delivered to a shop for repair if I realized this is way beyond me earlier, but have gone so far, with many things apart, would want to continue. Hey, I got the whole winter to deal with this!