Tecumseh 6.75 HP Jumped Time?

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  #1  
Old 09-07-08, 12:40 PM
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Tecumseh 6.75 HP Jumped Time?

I have a 1 year old 6.75 hp mower Tecumseh LEV120 that was given to me. It had hit a rock and broken the blade yoke. It would not start again after that. I figured that the problem was just the flywheel key had sheared off. To my surprise, it was ok. I tried it again and it feels like the timing is off (it kicks back during the pull stroke). I got one big backfire last night and that was it.

I got the service manual and it has gears that control the timing. Is it possible the timing gears jumped, or do they self destruct first? Are there any other common problems that may have happened in this scenario? If I tear the engine apart, do I need to buy any service gaskets and which ones do I need?

I have an old mower with the same engine that needs a ring job, so I could rob parts off of it if I needed to.

Thanks
 
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Old 09-07-08, 02:36 PM
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I doubt it is an internal issue.

1) By blade yoke are referring to blade adapter? Did you replace this.

2) Did you remove flywheel to inspect key or just starter cup?
 
  #3  
Old 09-07-08, 03:31 PM
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1. The piece that is broken is the part at the end of the output shaft that actually attaches the blade to the shaft. I did not replace it yet until I saw that the engine actually worked. I read on another forum that the blade needs to be on the engine for it to run. Is this really true, or will it just be hard to pull start?

2. Yes, I pulled the flywheel off the end of the crankshaft. No issues there.
 
  #4  
Old 09-07-08, 03:36 PM
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Yes the engine can be started without a blade installed, but it will be very hard to get started. It may also yank the rope violently out of your hand when trying to start. You will have to pull the starter rope, very quickly and hard to get the engine started without the blade installed.
 
  #5  
Old 09-07-08, 05:33 PM
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The engine will run. I would be concerned that the crankshaft was bent with the impact. I would remove spark plug and tie safety lever. This will allow you you turn crank shaft to visually inspect for a bent crank. Remove blade and adapter and measure from edge of deck to center of crankshaft hole. Turn crank 1/4 and measure, turn another 1/4 and measure and then turn final 1/4 and measure. If you are not getting same measurement crank is bent. If crank is not bent you must replace blade adapter and re-install blade and tighten. The adapter has a built in key and if that is sheared the crank will spin inside the adapter thus acting as though there is no blade and you will get the kickback from the starter rope
 
  #6  
Old 09-07-08, 06:36 PM
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Partial success. I put on the blade adapter from my spare mower and a blade. It fired right up...for a second. I primed it again, and it fired up and died. When it ran for those couple of seconds, it was perfect, so the engine is right, must be fuel delivery. I took the float bowl off and it was full. Fuel ran out of the orifice when the float was down, so no restriction there. The fuel stopped when the float was up, so the seat is decent. I flooded the carb from the air end and up the middle of the float bowl with carb cleaner, as it has sat unused for a few years. It cranked again and ran perfect until the carb cleaner ran out and died. I repeated priming and starting it for 20 or so cycles with the same result. Any guesses? Could the inital backfire have blown anything out in this type of carb?
 
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Old 09-07-08, 07:14 PM
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If it sat for a couple of years unused, then there is the possibility that the carburetor may need a good through cleaning, and the O-Ring seals on the nozzle may not be any good and may need to be replaced.

The fuel thats in the tank, is it also a couple of years old??
 
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Old 09-08-08, 06:34 PM
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The only seat that looked questionable was the one that the float bowl nut seated on. I will buy a repair kit for the carb this weekend and replace the rubber parts. Any place online you would recommend?
 
  #9  
Old 09-08-08, 06:53 PM
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I use several places, just google Tecumseh parts and you will get quite a selection of places. I would recommend a local shop, as when shipping is added you can usually save by purchasing locally.
 
  #10  
Old 09-08-08, 08:18 PM
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I had the same problem recently. I cleaned the carb ten times. The engine was still dying a few seconds. It was not a carb problem. I changed the spark plug not knowing what else to do and that was the answer.

Good luck
 
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