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Good Spark and clean carb but still no start

1863 Views 8 Replies 4 Participants Last post by  westislandbrewer

I have a Tecumseh lawnmower model TVS 43745n. I crank the cord but it wont start. The spark plug gives a good spark. I have undone the carb bowl, gave everything a good cleaning including the jet holes but still no start. I even tried putting a tablespoon of gas in the engine and cranked it with no luck. I also have fresh gas. Does anyone have any suggestions that I might try to get this mower working. Thanks in advance, Philip
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Check to see if the flywheel key is sheared. Modern ignitions will still produce a spark but be out of time if the key is sheared.
Check the compression, it may not be high enough for the engine to fire. It's the case of you must have 3 to get 2, you need fuel, spark and compression to get smoke and noise. Have a good one. Geo
Piston does not go up and down

I took off the head cover and I noticed that the valves open and close when I turn the blade but the piston does not move. I checked the flywheel key and it is fine. Is it possible that something connected to the piston is broken?
Most likely you have a broken connecting rod. You would need to tear down the engine and inspect to see if it's worth repairing or not. Any damage to the crankshaft at any of the journals or the bearing surfaces of the block and it would probably not be a cost effective repair.
Thanks guys...

took off the bottom plate and the connecting rod and camshaft are broken. Parts are ordered on ebay and I should be up and running soon. Thanks for all the suggestions and help. Philip
Camshaft and Connecting rod Replaced but other issues persist


I have a Tecumseh lawnmower and my connecting rod and camshaft broke as the result of hitting a solid object. Only my teenage son knows
what it is!!! Isn't the flywheel key suppose to break first? It didn't, it's not even slightly bent. Anyway I digress. My question is
I don't know how to reassemble the oil pump part. I know it fits on the bottom end of the camshaft but where do I position the small rod
with the round end? Any help would be much appreciated.

Kind Regards,

Philip from Montreal
The camshaft broke when the connecting rod came loose, this did not happen from hitting anything. The rod was either loose, or had damage from lack of lubrication.

The pump rod plunger fits into the oil sump, there is a circular casting with a slot for the rod to fit in.

Here is an illustration of what I am referring to.
30yrtech....Thank you

Thanks to your help and pdf attachment I was able to get my oil pump back on properly. Thank you so much. If you send me your paypal account I will send you a small gift as a token of my appreciation for the time you took to help me out.

Kind Regards,

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