Small Engines (Lawn Mowers, etc.): Eager-1 Start Problem, eager 1, little holes

Question
QUESTION: I salvaged an Eager-1 lawnmower, Model # 917.974143.  I have it running, once I get it to start.  To start, I spray a starter fluid, then carb  cleaner into the air inlet.  Once running awhile, it runs and cuts OK.  If I try to replace the air filter, it chokes off and dies.  Any ideas?   Jim.

ANSWER: From the parts blowup, it looks like a Tecumseh Engine, does it have a primer bulb?  The primer not work?  Have you tried a new air filter?  Is the fuel in the tank old, I would definitely put in fresh, drop the bowl on the carb and clean the bowl nut and the little holes in it, try this
and let me know what you find, and find the engine's model numbers.
  Thanks

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QUESTION: I haven't been able to locate an engine model #, but it does have a primer bulb, I think its a Tecumseh.  I cleaned the air filter, but when it is running if I even get close with the air filter, or anything else, like my hand, it dies.  I've cleaned the bowl nut twice.  It has fresh gas.  Another thing, the spark plug was fouled with black, hard deposit, so I replaced.  How would I check the primer?

Answer
By blocking the intake, it should choke the engine down and deliver more fuel, and the engine would run longer with a fresh dose of fuel, so something is wrong.  See if the carb pieces
move freely, they may be gummed up.  I am thinking this mower has been sitting for years and the valves are gummed up.