Hi there, someone recently gave me a sickle bar mower with a 5hp Briggs&stratton engine. I got it running fairly easily but the engine sounds like "vroooom.......vroooom.......vrooom", with a pause in between. Kind of like an inconsistent idle, going up and down. My question is, if I were to pull the carb bowl off, do I first need to drain the entire gas tank, meaning will the entire contents of the fuel tank spill out once I remove the bowl? Any other ideas as to what might cause this sound are welcome. Thanks!

Post the engine model, type and code usually found on the engine shroud just above the sparkplug. You should be able to clamp off the fuel line so it won't drain. Sounds like the carb needs cleaning. Have a good one. Geo

Why don't you try adjusting the carb. before doing anything else. If the fuel is questionable I'd drain the tank and the fuel bowl. Clean everything and fill with clean fuel. Try starting it then..adjust the carb. Should be good to go.

Jake...

Fuel is brand new and very fresh. Not sure how to adjust the carb though. Engine model is a 5hp quantum. Not sure of the number, will check when I get home later. I did remove the air filter and spray carb & choke cleaner in the throat while it was running. I will remove the bowl tonight. Any advice on how these are attached? Do they just screw off??

the bowl is held on from under it with a brass bolt most of the time should take a 1/2" Use a 6 point shallow socket if you can to avoid stripping it. once the bolt is removed then grab ahold of the bowl and gently rock it . I would suggest taking the carb completly off and cleaning it.