Smell the oil for the presence of gas. that would indicate fuel leaking through the needle/seat assembly. However, if it's a fuel pump engine, it may only empty the fuel line. That relatively small amount could easily get missed. IF the carb solenoid is leaking, you should be able to see it unless it's very slow. A few things you can check/try. Make sure the choke plate is fully closing on the carb. After the mower has sat for the "usual" extended period of time, remove the carb bowl and see if it's empty. That would tell you if it's leaking out or not. Try priming the carb first with 2-3 teaspoons of gas and see if it fires "right up".

rcmoser.... Yes, changing oil frequently is good. I actually change the oil every 25 hours of engine time. Every 50 hours, I change the oil filter too. That makes 6 oil changes per year.... We don't often get feedback as to how effective frequent oil changes are in preserving our engines. I recently had to disassemble my 26 hp Briggs Intek V-twin to replace a leaking sump gasket. The engine has been mine since new, with the above oil change schedule. Currently the hour meter reads 751 hours. Below, I will post two pictures of what my 'lower end' looked like when I cracked it open, for the first time, last month (before any cleanup). In the pictures you can see the sump gasket pieces scattered all over the sump and block. Other than the gasket pieces the 'lower end' is perfectly clean. Not a sign of any gunk or sludge could be found. Now I know why Briggs designed the engine with that oil screen in the bottom of the sump. The purpose of the screen is to prevent pieces of their cheap and poorly applied sump gasket from reaching the oil pump!

Hey guys - I just read through all these posting since I have the same issue. Just bought a used Yard General with the 20HP Vanguard. Cut the yard twice beautifully - starts like it should, runs like it should. The last time I let it run out of gas. Once I refilled, it started up (not without a little effort to get gas back to the pump I suppose). It only ran about 20 seconds till I engaged the blades, and she started stalling till finally died. Wouldn't start till I pulled the gas line going TO the filter, let it drain out of the filter, tried and it started right up, for 20 more seconds. Same issue - won't start. Here's the strange thing - I can hear and see a rhythmic squirting sound from the carb, and see pooled gas in the bottom that gets disturbed each time I hear the sound. Its like the fuel pump is squirting gas in - all while nothing is running and battery disconnected. Thought at first it was vapor lock - took off the cap, pulled on the diaphram there, thought it was fixed, but died again. Anyone got any ideas? If the fuel pump loses its prime, is there some special procedure to follow? Thanks in advance! Mike

"Is the brake caliper hooked to the flywheel on this thing?" Yes it is. By means of the drive belt. The OP stated the the engine seems to run at slower RPM than before the heat treatment and that now executing turns has an effect on RPM/power, depending on which way you turn. I can only correlate that to something that would affect how much effort is required to move the machine across terrain. It IS NOT that the engine really makes more power during turns,m it is because the loading of the engine changes during turns (due to a sticking brake caliper). After I posted last night I also realized that it is entirely possible that this V-Twin Vanguard engine might only have 1 cylinder making good power. With only 1 cylinder putting out good power, the other cylinder constitutes an added load, thereby lowering RPM.......and making the engine run at full open throttle but never really reaching governed RPM. Hence the engine is able to speed up some when conditions occur that lessen the total loading.......or to "bog down" easier when loading increases. And a sticking brake caliper is capable of doing that. Vanguard twins can lose a cylinder entirely and the exhaust note will not sound much different, so it is not as apparent that you only have 1 good cylinder remaining. Heck, it's easier to detect an intermittent misfire than a completely absent cylinder on a Vanguard Twin just using the ears. This post was edited by mownie on Fri, Sep 13, 13 at 11:33