Modern Vespa

Background: Last summer my scooter (2006 GTS250) started to exhibit the classic signs of a fuel pump failure. It would not start when had been running for a while, shutdown and then fail to start. Dumping cool gas in tank would allow restart. So a new fuel pump was the solution.

Replaced fuel pump over winter and first ride out after 50 miles I stopped for a sandwich and scooter would not restart. Waited about 20 min and scooter restarted.

Decided to put a new fuel injector in as pump was new, so why happening? During fuel injector replacement, I found a spot on the fuel supply line where the thick insulation was worn off exposing the actual fuel line. For a temporary fix, I tywrapped heavy rubber tubing over that area while waiting for a new line.

I have gone for several rides with this repair and never had the non-start issue repeat. So, here's my theory: When things got warm and then shutdown, with the fuel line exposed the fuel would vaporize and form a vapor block until it cooled back to liquid form.

Thoughts?

What does it do when it doesn't start? click? crank over? Nothing at all?

You said the fuel line insulation looked "worn off". Is it possible it was actually melted off?

If the line is touching something it shouldn't and locally getting very hot, it would support the idea of fuel vaporization.

Do you have any photos?

Cranks but doesn't catch.

Insulation worn off and I will try to get a picture.

It certainly is a possibility as you changed something and the problem went away. Yes, post a pic, learning something new is always helpful. Good eyes, by the way.