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Tecumseh 5.5hp Vector engine. Hard start but runs fine when does. Need help!


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09-04-13, 05:59 PM   #1  
Tecumseh 5.5hp Vector engine. Hard start but runs fine when does. Need help!

Hello. I have a Tecumseh 5.5 hp vector engine on my Ariens LM21 mower. It has the Tecumseh carb with the machined aluminum body and the plastic float bowl. The mower has been hard to start the last few months. I push the primer bulb 5-6 times but then still have to pull the starter rope 6 or 7 times before it will start. It's a little rough for a few seconds but then smooths out and runs fine. It always restarts fine when warm after I shut off to empty the bag. Only issue is when the mower is cold. Last year I replaced the flywheel key as it sheared and mower ran poorly. It was fine after that. I also replaced the float bowl assy. about 2 years ago (aftermarket) and it started and ran fine after that. I have been playing with it the past few days. The primer bulb is in the air filter housing. I had a new one so I replaced it. Could not see a problem with the old one after I removed it. I had the air cleaner housing off to check things and replaced the gasket (new) where it mates to the carb body when I reassembled things. After these things were done, it still would not start any better but runs fine when it does. I f I spray a little starter fluid in the spark plug hole, it will start. Plug is not wet when I remove. Did a little internet research yesterday. Apparently the air filter housing is subject to damage/deformation. Today I took the air filter out but left the housing on carb. When I press the primer bulb a few times, I can see fuel come out of carb into housing (dribbles) so I believe the primer is working OK. I took the housing off carb, blew air into the hole in the aluminum carb block where the primer passage lines up with. I can see fuel shoot up the center of carb like it is supposed to. Reassembled everything carefully and did not overtighten. Cleaned plug. Checked, has white/yellow spark. Still does not start on first or 2nd pull like it used to when I primed a few times in the past. I sprayed starter fluid around the carb while running, speed does not change (only does if I spray in the air intake) so I believe there are no vacuum leaks. I am at a loss at this point. What am I missing? Is it possible the spark should be hotter (bad plug but enough spark once it gets going to stay running)? Could the keyway be sheared again? Like I said, it runs fine once it gets going, it just does not start easy unless already warmed up. Thanks for your help. I can attach pictures if need be. The Tecumseh carb # is 632671C. - TSPORT

 
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09-04-13, 06:07 PM   #2  
Spark should be blue not yellow.
Whens the last time the carburetors been rebuilt?

 
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09-04-13, 06:25 PM   #3  
If spark should be blue, I guess I will try a new plug first. Carb has not been "rebuilt". The float bowl assy. I replaced last year with new contains all of the internals for this carb. The only part left to the carb is the machined aluminum block which has a few passages in it and the throttle valve which is fine. I have not had the float bowl off since I replaced it.

 
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09-04-13, 09:31 PM   #4  
Sounds like the primer isn't working. Check to be sure it is seated tight and fully in it's housing. If the tiny pulse of air pushed by the primer leaks somewhere else, it won't pressurize the bowl and squirt a little fuel in the throat of the carb.


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