Page 1 of 1

fuel vacuum line

Posted: Sat Aug 06, 2022 5:07 pm
by zpyroro
New here, thanks for adding me. Would anyone know why I have to suck on the fuel vacuum line to fill the carb after my 1985 scooter sits for more than maybe a week or so. After I do that the engine starts right up. Your help is greatly appreciated, this has been a on going problem ever since I bought it about five years ago.

Re: fuel vacuum line

Posted: Sun Aug 07, 2022 1:42 pm
by Wheelman-111
Greetings;

It doesn't say where you live, but I'll bet it's hot!
Carb is tiny, bowl vent allows for some evaporation, and gets to a point where the Jets can't suck enough fuel for combustion.
The various lines that cover the vents on a new scooter help a bit, but I have them and have the same issue you do, especially in summer.
It's just Honda-san's way of making you ride every day!

Re: fuel vacuum line

Posted: Fri Sep 23, 2022 11:24 am
by AKAspree85
I had this problem with my '85, it turned out the little rubber "hat" where the throttle cable goes into the carb didn't fit right allowing for the the gas in the carb to evaporate more quickly, but not enough to cause issues with it running.

Re: fuel vacuum line

Posted: Tue Oct 04, 2022 10:24 pm
by Rideslikenacho
Mine does same, tried adding a bulb style primer to the vacuum line to pull suction and that didn’t work. On the afternarket carbs I ‘believe’ that back/engine side has a vacuum line on it. Maybe could add a Y shaped fitting and run a line to the manifold vacuum and also the carb vacuum to pull more suction. I’ll be trying this next.