Hi, i have a yamaha 250 from 78? mabey im not quite sure but it shouldnt matter.
The snowmobile runs fine when the hood is open...but as soon as i close the hood the engine dies. Has anyone had a simular problem or knows an easy fix that doesn't require leaving the hood open would be greatly appreciated.

There is no airbox on that machine right? Do you possibly have an exaust leak and when you shut the hood it chokes out from the exaust? I dunno just an idea.