OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Tecumseh / Kirby Engines Tecumseh TSV90

Hi Peter, the tube you're refering to is just an extension of the breather vent hole in the carby, they tend to fall off, break off or melt away with time with little or no effect to the rest of the carb.
The mixture screw should be set at one and a half turns out initially and adjusted in quarter turn increments at full throttle once the engine has warmed up. This process will definitely have it running sweet at full revs and hopefully the idle will follow suit.
If it doesn't i could only speculate that the carby needs another thorough clean, paying particular attention to the small hole at the top of the jet, there is a leak from one of the gaskets or the wrong primer bulb has been fitted. Test the primer first by starting the mower and setting the trottle to idle, then block the hole in the primer with your finger and see if that improves how it runs at idle.