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STEVEN DRUM

Craftsman Lawn Tractor Model No. 917.28728 - will not start

Well-maintained, four-year old lawn mower will crank but doesn't turn over when trying to start it. It started fine in June, would not start in September and still will not start after changing out the spark plug, fuel filter, and battery (air filter is fine). Fuel in tank had stabilizer added, but have also tried adding Sea Foam.

Any suggestions? Thanks.

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Craftsman , Lawn Tractors , Lawn Mowers
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6 Answers from these members:
Manage My Life
Since the fuel filter is new, the problem is probably in the carburetor. the carburetor on your engine is more complicated than some. I recommend you go to services.sears.com/shs/category/repair?sid=MMLxexpertxmerch and get a Sears tech to repair the tractor.
by Manage My Life
May 13th, 2011
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STEVEN DRUM
Thanks for your help, Jimmy. I just couldn't understand how I could develop such serious issues with it doing nothing but just sitting over a three month period. So I went back down the checklist and, although I honestly thought the spark plug was wet after trying to start the engine earlier, I must have been mistaken as they were dry on my re-test. I shot a squirt of gas in the spark plug holes, put them back in and it did start up, though only for a couple seconds. So, looks like my issue is fuel not getting to the spark plugs. Any more ideas I can try before calling in the repairman?
by STEVEN DRUM
May 12th, 2011
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Manage My Life
If the spark plug is wet after trying to start the engine, and you do have spark, the engine is probably firing out of time. There could also be a problem with the rocker arms and valves in the head.

To check the timing remove the blower housing from the top of the engine and remove the flywheel nut. This nut is torqued to 240 inch lbs and is hard to remove. You probably need someone to hold a large flatblade screwdriver in the teeth of the ring gear while you remove the nut. An impact driver makes this much easier.

With the nut removed, you can check the alignment of the groove inside the flywheel with the groove in the engine crankshaft. If the 2 grooves are not perfectly aligned, the flywheel key is sheared and the engine is out of time.

Remove the valve covers on top of the cylinders and rotate the engine by hand while you watch the rocker arms raise and lower. The rocker arms should move about the same distance up. If one rocker arm is barely moving, the lobe on the camshaft inside the engine is worn down.

Replacing the cam shaft inside the engine is a major repair and you probably need to get a technician to do this repair.

If you have more questions, reply on this thread and I will be glad to help.
by Manage My Life
May 10th, 2011
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STEVEN DRUM
Checked spark plug after trying to start and it was wet. Kept out and tried restarting and did get a spark. Still befuddled.
by STEVEN DRUM
May 9th, 2011
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Manage My Life
You need to determine if the problem is not getting fuel to the cylinder or not getting fire to the spark plug.

An easy way to do this is to engage the parking brake, shift to neutral, engage the choke, and crank the engine over 4-5 times. Remove the spark plug and inspect it. If the plug is wet with gas, the problem is no fire. If the bottom of the spark plug is dry, the problem is no fuel.

Your tractor has 2 safety switches that can short out the ignition module and kill the spark to the spark plug. If the spark plug was wet, remove the 2 black wires from both switches and crank the engine. If the engine starts one or both switches is bad.

The clutch/brake switch is mounted on the frame near the clutch/brake rod. The switch is made or broken when you push the clutch/brake pedal down.

The attachment clutch switch is mounted on the bracket for the clutch engagement lever. This switch is made or broken when you engage or disengage the deck.

Leave the white wires on the switches when testing. Remove only the black wires from the switches.

Fuel additives are not recommended for air cooled engines. Products such as Sea Foam will cause deposits on the valves and damage the carburetor. I suggest draining the gas and putting fresh gas with stabilizer in it in the tank. These engines run much hotter than water cooled engines and additives don't work well in them.
by Manage My Life
May 6th, 2011
Answered in 16 hours
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Joseph Perez
I know how great it can be to have a good working tractor in the home so that you can keep your grass nice and trimmed. While you are waiting for your expert answer, I did manage to find a link that will provide you with some good tips to help you with your tractor problem. I hope my link is useful.
by Joseph Perez Earned 1,551 community points in Craftsman
May 5th, 2011
Answered in 7 minutes
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