I'd try another temporary fuel tank first, to eliminate any questions about if it will run or not. If it runs, say for ten minutes with the auxiliary tank, then it will eliminate problems with the carb. Next thing i'd check is the breather hole in the gas cap. In fact, i'd do that first, then the aux. tank. Next would be to do a thorough cleaning of the tank, for a floater, or sinking floater, that might have found its way into the tank. See if the fuel pump does pump fuel thru itself-that is-see if it works, by cranking the engine with the plug wire off, and the pump outlet hose off its nipple on the carb. Just be careful, watch for squirting gas, as it will ignite fast! Don't burn yer house or garage down! Safety is king in this situation! I tender these suggestions with the assumption that you know the dangers of escaping gasoline, and its affinity of igniting from the careless cigarette in somebody's hand! Or mouth! (Sheesh!!) All safety precautions must be followed! HTH: Rusty J.

tps, at least you learned some things that you can use to your advantage in the future. Products such as Seafoam are more intended to PREVENT the formation of new varnish than for trying to "scrub away" old, solid varnish. As you mentioned in your second post, you suspected the machine had been sitting in storage for a while. That will create the most stubborn kind of varnish. Seafoam can handle relatively fresh varnish/gum (which can obstruct fuel flow too). For the hardened and "cured" varnish, it typically requires products like the Berryman B-12 or other brands such as Carb Medic or Gumout (just to name a couple). For the "worst cases", a professional shop might even prefer to use a "dip bucket" cleaner such as "Berryman Chem-Dip" or the classic Solder Seal "Gunk Dip". You can still use the Seafoam as an additive to your fuel. Beware, if the "old" fuel lines are still in place on this machine, there's a chance that some particles/debris can continue to "slough off" and make their way to the filter. Also, if the lines leading from the filter>fuel pump>carb are old......any particles/debris shed from them will be transported right into the fuel pump and on to the carb. If a pieces of debris get caught between the needle valve and valve seat (carb inlet), there is a chance that blockage can occur or the needle valve can't control the fuel flow. You should replace at least the sections of fuel hose between the filter> pump> carb inlet to minimize the chances of that happening. The hose between the filter and fuel tank is probably ok for continued service (unless you see cracks in the hose surface) as the filter will trap the debris. If you want to "go all out" on the recovery process, replace ALL the fuel hoses AND remove the fuel tank for a good cleaning with the spray carb cleaner. This will get rid of any "flakes" or "sheets" of varnish that might be stuck to the interior surfaces of the tank.

I had the exact same issue...replaced fuel pump, spark plug, cleaned fuel lines and replaced fuel still no start. Turns out the intake valve push rod (aluminum) was bent... replaced it and re-gapped the valve rocker arms and the engine started immediately! Anyone know why B&S used aluminum valve push rod? Answer: IT ALWAYS BENDS! Very poor design I think. I've never seen that in a car or ANY other mower I've owned in the last 50 years.

Well, I thought this problem had solved itself. The thing started well most of last year and until this week. I thought it had a stuck ring or valve, or a little bit of varnish from the modern gasoline. Anyway, I installed two champion CJ8 s, gapped to .025. And it started right off. Changing from NGK BMR4As Lot's of good comments on this thread. It's a little over my head. I'm assuming that if the composite camshaft gear breaks, it's definitely not going to run, correct? And further regarding this thing, is this gear failure always a fairly benign thing? That is nothing else gets bent or damaged when this thing goes? I had the case cover off to repair the inner gasket to prevent water from leaking into the crankcase, actually I don't think it ever went into the crankcase, but it eventually would not hold water even to mow the yard once. I then, wasn't aware of this issue with the composite gear and I'm not totally sure if it has the composite or not. I seem to remember looking at a brown fiber gear-looking thing. But I'm not sure. Thanks for all the comments, and I think it's just the spark plugs causing this problem. Although I'm not sure why long cranking worked to get it to start. Anyway...Cheers!