Modern Vespa

My 06 LX150 stalled at a light earlier, after running fine all day..
It started fine, but upon giving it gas, no power ..it'll big a bit, and give a few small backfires.
The gas lines look like it's feeding fine, and it idles just fine...but as soon as I give 'er some gas, bogs and sputters.

Its obviously starving for either Air or Gas, and after looking, I realized there's what appears to be one of those gas diaphragm feed systems at the bottom of the tank...I'm thinking this may be the problem...



Any input greatly appreciated!

Joe

You have a vacuum operated fuel tap below the tank. One hose is vacuum and the other is fuel line. Make sure the vacuum hose is free of holes or cracks.

They had the same system on a U.S. built scooter that was lost to Hurricane Katrina- the plant was wiped out.
I had a little Vento Triton 50cc; built around the time they started making them look like some cross between a crouch rocket and a Star Wars toy-

Same thing happened, and the scooter 'tech' said it was due to higher octane gas- which I thought was odd; but he claimed the higher octane gas deteriorated the seals...
I replaced it and it was fine.

I just got my LX a few weeks back, so I'm still getting used to it and whatever quirks may popup.The guy I got it from had it serviced on a regular basis at the local Vespa Dealer where he bought it; and he didn't have any specific info on What was replaced or fixed.

on a bike of that age I'd be looking at all the rubber components, especially those in contact with oil or gas.

namely, the vacuum and fuel lines. the vacuum is especially prone to failure so check the full run of it- tap, to the T junction, and from there to the intake manifold and SAS gulp valve connection. sometimes they deteriorate within the protective sheath, but generally it's right at the tap or on the run from the T junction to the SAS. fuel lines just age out so look closely and make sure you're not sucking air.

inspect the intake manifold for cracks. replace if necessary and refresh the gasket if it takes one.

if the bike has never had the fuel tap replaced, I'd recommend a new one just due to age. one that is on its way out is a pain and one that flat ass fails can be a safety hazard.

besides the obvious of going thru the carb and making sure it's clean and free from obstructions you may also want to check your plug cap, the plug itself and the connections to the coil.

at the coil, the connections can sometimes corrode causing an intermittent running problem. the plug caps can wear and sometimes crack. also, if somebody was hamfisting around in there they may have jostled the HT lead loose. on the plug besides a visual of the electrode, check the porcelain for cracks and the nipple for wear (and if that type uses a removable one for tightness).

if you don't have any solid service history you may want to start with a baseline and get a general service out of the way to start.

anyway, it all just may be an overfilled gas tank or bad/saturated air filter. so check the easy stuff first!

hth