I’ve got a 72 elan with tillotson carb. Carb was cleaned and new fuel. In tank. New plug. It starts right up with ether and will stay running for a few seconds with gas in cylinder. Any idea why it won’t stay running?
Clear fuel line can help you see if it's getting to the carb , if it's not try flipping the diaphragm in the fuel pump. Check or put in a new fuel filter.
Check the impulse line from the crank case to the pump body
It looks like a primer line is T'd into the main fuel line below the fuel filter. Make sure that primer and line is not letting any air into the main fuel line.
The first snowmobile I bought was a brand new 1971 Elan. After I had a couple hours running time on it, it would run a minute and stop. There was plastic shavings from the fuel tank clogging up the fuel filter.