I caught myself in a definition trap. My first thought, when I spotted the explanation that the poorly running engine could be caused by a bad vacuum tube, was to the old vacuum tube radios of my youth. Even with that blunder, the old vacuum operated windshield wipers of my first cars offered the explanation – but I didn’t see it immediately.
The early riding lawn mowers, like the model T, didn’t have fuel pumps. The tank was placed higher than the engine, and gravity took care of getting the fuel to the carb. That’s why they have the old stories of cars climbing hills in reverse – going forward on steep climbs put the gas tank lower than the carb, and the engine would die.
My education started with the realization that new carburetors for 2 cylinder Briggs engines were available for about $25 – not much more than a carb kit, and, given the neuropathy that came with surviving cancer, a much larger part for my fumbling fingers to replace. The engine ran fine during the heat of the summer – but as I encountered near freezing temperatures, the loping problem returned. It’s got spark, it has air, the carb is new, let’s check the fuel pump.
The fuel pump, like my old windshield wipers, runs on vacuum – and when I removed the vacuum rubber hose (yes, the vacuum tube) I learned that it had developed cracks and leaks. I was having to use starting fluid to start the engine because it couldn’t develop enough vacuum to pump the gas until the engine was running.
Well, it was $3.63 for the new vacuum tube and $12.00 for shipping. Since the mower is 11 years old, I figure next time it will be someone else’s problem – and I’d like to share the solution with everyone I can. It’s a bit embarrassing to realize that the definition I was using became obsolete before I turned 21. At least I have gotten past that blunder.