Engine Starting Problem


Old 10-27-02, 10:39 AM
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Question tecumseh enginewill not start

I have a 10hp tecumseh vertical engine with electric start, that will not start, i checked for spark- good. Compression is good. The carb was cloged and the float was sticking so i clean it with carb cleaner but still will not start. The engine has also been sitting for a while. I tried to spray some engine start and still will not start. Sometimes all it will do is back fire.
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Old 10-27-02, 03:37 PM
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This may not be it but check it anyway. Not that hard to do. Remove the flywheel cover and the large retaining nut on the flywheel. If you can't see the keyway in the slot in the crankshaft well enough without removing the flywheel,do so. What you are doing is checking the keyway to insure it hasn't been partially or totally broken. Either will prevent the engine from starting. That's what keeps it in time. Even if it looks like it's been forced out of square just a tad,replace it.
Old 10-27-02, 03:54 PM
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Does the sparkplug get wet when it is turning over? No gas from the carb...

My guess is the carberator needs to be taken apart and cleaned.
Old 10-27-02, 04:47 PM
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10HP Won't Start

Good posts from BobQ and Dave4.3.....The backfiring could very
well have sheared the key, but if the engine has been sitting for
a long time WITH old gas in the fuel system....I've SO MANY that
will require a CARB REPLACEMENT vs. a good cleaning. The old
varnished fuel may also have the valve(s) sticking in the guides,
so this may need attention, also. You say "good compression"....
What is your GOOD compression reading ?? If you have GOOD
compression and GOOD spark....the engine should run for a short
brief period if you squirt fuel or starting fluid into the intake.....Is
this happening ?? If not....then there is a compression/valve train
issue, and possibly an ignition issue, too....Check it all out and let
us know how we can further assist.

Old 10-27-02, 06:19 PM
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Yes, it's a good idea to check all those things. The backfiring got me thinking about the key,opposed to the valves. I've seen so many times where people will totally dismantle an engine,not being aware of the key being the "key" to the whole problem.
Sitting for a while will definitely gum up the works though. Both at home and at work I'm never low on Sta-Bil.
Old 10-27-02, 07:25 PM
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Many Good Thoughts Here....

Any one of the thoughts here could be the problem with this engine. I would lean toward a frozen valve......Mike
Old 10-27-02, 08:01 PM
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Thanks for all the replies. I was checking the valves and the piston thru the spark plug hole and saw that every time the piston is on its way up (close to the bottom of its stroke), during the compression stroke, the spark is going to fire. Both the magnet on the flywheel and the coil are lined up. So i guess that the key on the crank is missing or broken. I have not removed anything yet. Do you need a special puller tool to remove the flywheel? Thanks
Old 10-27-02, 10:41 PM
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You know that the coil sparks twice in four strokes?

The key doesn't break unless you have hit something.

If the flywheel is cast iron hit it with a hammer on the opposite side to the magnets. If it is aluminum you should use a puller. The hammer trick will work but not recomended. You can also buy a cheap knock off tool(I think I paid 3 bucks). It sits on the end of the crank shaft and you hit it with a hammer while using a screwdriver to pull up on the backside of the flywheel. It works alright.
Old 10-28-02, 05:29 AM
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Sheared Key


With the piston at top dead center, the magnet on the flywheel
will just be to the left of the coil legs. If the magnet is between
the coil legs @ TDC, then the flywheel key is DEFINITELY sheared.
If the magnet is just to the left of the 2 legs of the ignition coil
with the piston @ TDC....then you should look to problems OTHER
THAN a sheared key. This will keep you from having to pull the


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