Garelli SSxl fuel petcock/fuel line problem

Jason Kofke /


I am newish to mopeds, finally owning one after borrowing off and on over the years. So now I need to do my own repairs...

I just picked up a very custom Garelli SS 1978 with lots of cool alterations. But after riding it around for an hour, it started to peeter out. I noticed that the fuel lines seem empty coming out of the top tank all the way to the carb. There is an in-line filter right after the top tank but the fuel isn't even making it to it - there seems to be no fuel running out of the tank/petcock. My thought is that maybe there is junk in the intake from the tank (I have no idea how it works in there) or that the petcock is messed up. It is the 3-toggle petcock that has a closed/open/reserve setting (though I'm not sure which is 'reserve') I was dumb and unscrewed the black knob from the petcock to see what's in there only to have a spring and metal disk pop out and gas running out all over me. I put that all back together (I hope) correctly. It seems to have a slight leak either from the petcock or from the line attached to the petcock after messing with it.

Do I need to replace the petcock? How do I check if there is a problem inside the tank? The fuel is a bit old but looks clean (about a half tank in there.) Or is it another problem like the carb isn't sucking in fuel or air filter junked up? What would be your first moves to trouble shoot. Before the lack of fuel in the line, this Garelli was running along perfectly. Thanks!


Re: Garelli SSxl fuel petcock/fuel line problem

Just buy a new petcock. They're cheap, and easy to install.

Re: Garelli SSxl fuel petcock/fuel line problem

Try disconnecting the fuel hose from the filter . Still no gas coming out ?

Blow into the hose , which should force anything blocking the line back into the tank .

There will likely be a stream of fuel once there's no back pressure ( you blowing ) .

If that frees the flow , it should be good for a little while , until the blockage reseats itself .

Or , you could lean the bike to the left while you pull the petcock for inspection / cleaning . At least , you'll learn what's inside . ;)

Re: Garelli SSxl fuel petcock/fuel line problem

Also as a tip, If you tank has any bit of rust in it I would avoid using the reserve setting on the petcock. It draws from the bottom of the tank where all the shit gathers which can create blockages.

Re: Garelli SSxl fuel petcock/fuel line problem

Jason Kofke /
1979 OP

ugh. I've been wrapping my mind for a quick and easy way to test the petcock/lines without disassembly. You're brilliant. I am dumb not thinking of this. thanks!

Re: Garelli SSxl fuel petcock/fuel line problem

That type of gas caps on those really suck! The cork in those dry up after swelling up and closes the vent up which creates a vacuum. The next time it acts up loosen the gas cap and see if it runs better.

Re: Garelli SSxl fuel petcock/fuel line problem

your carb doesnt suck fuel, its all gravity, so if fuel dont come out then its blocked, maybe its missing its filter and clogged w goo, u cant see it till u pull it off, or maybe the rubber gasket is buggered and blocking one of the holes preventing flow (side note: ive cleaned and flipped that rubber disc so it seals again), or maybe it was put together with that metal disc flipped so it obly wotks in one position. new ones are pretty cheap.

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