Originally Posted by S10xGN
Both my "problem start" engines have that funky zero-adjustable carb that's half inside the fuel tank. I got a chance to spark-check one and the coil is weak, so I'm gonna look for another coil. These both started great the first two years, now the tank has to be refilled during a mow where it used to cut the yard 3 x's on one tank when new. New plug, cleaned air cleaner, no air cleaner - doesn't matter, it still takes forever to start. Also, they run smooth with no load, but once they hit a load they start "hunting" and on the down-rev side, they blow a black puff out the exhaust. I bought a new mower, but plan on turning this old one into a vacuum so I don't have to spend so much time cleaning up the clippings...
Several things jump out at me here.
There were several variations of the fuel tank/carb you describe, but I'm guessing that you have the older "automatic" choke version (the choke plate appears to be spring loaded if moved?). if so, you're money ahead by tossing it in the trash and stopping by your local small engine shop to see if you can pick up a later model used assembly with the built in primer on the side. most shops will have a few laying around in the back shed for cheep. pick up a new diaphragm/gasket set wile your there, just for insurance. the whole deal shouldn't put you back more than $20.00 or so, and it makes a night and day difference in ease of starting. it's a straight bolt on deal.
I'm also guessing you have solid state ignition on yours? is the area between the coil windings and lamination filled in on one side? if so, that's a solid state coil assembly. if it's open on both sides of the windings, then you have points and condenser under the flywheel. if your have points, pick up a conversion kit (made by B&S). it's cheeper than a set of points, and works way better. if you already have SS than leave it alone. the coil either works or it doesn't, but will never be "weak" (ok…. 1 in 500,000,00 it might be weak).
one more little tidbit: you're engine won't run correctly without an air filter screw
installed. the hold down screw goes straight through into the fuel tank, and if the tank is near full, it will pull raw fuel up the screw hole and make it puff smoke, or just die completely when any load it put on the engine.
There. now you know everything I know from 40+ years in the business. do you feel smarter?