Modern Vespa

i recently bought a 2007 lx15o with a 100 miles on it. i have driven it for a few hundred mile until it started stalling out. i thought that the carb might be dirty so i added sea foam and ran it a few times.

now it turns over sometimes but when it does the idle is very erradic until it stalls and then it won't turn over again until i leave it for a day or so and does the same thing again.

i am kinda lost now and don't know what to do so i could use some advice.

I am not an expert but I had the same prob with my GT200. I disconnected the evap system an problem solved.

It could indeed be the evap system, but I'd also pull the idle jet out and give it a proper cleaning. There are some clogs even SeaFoam won't dissolve!

i disconnected the evap tube that ran to the carb. it now runs consistently, but with little power, erratic idle, some white smoke out of the muffler, and drips of gas out the evap connection on the carb. i am planning on pulling the carb and cleaning the idle jet. this could still be the issue, right?

thanks again for the help

Hmm. A clogged idle jet could certainly account for the erratic idle, but the white smoke and drips from the evap connection on the carb are a mystery.

White exhaust smoke is common on any internal combustion engine until it warms up, especially in certain weather conditions. It's usually just water vapor.

A carb shouldn't drip gas. Perhaps you have a stuck float, or have a float that isn't floating anymore (happens on hollow floats sometimes), or you have gunk blocking the float valve from closing all the way onto its seat. You need to open up the carb, see what's wrong, clean it out, fix it, and put it all back together. If you're handy with tools and are familiar with carburetors you should have no problems; if you're not handy with tools you should probably take this to a scooter mechanic or dealer to get diagnosed and fixed. Also, you may want to install a better fuel filter.

I have zero experience with scooter carbs, but I have decades of experience with car, truck, and mower/tractor carbs. On every other engine with a vapor recovery system that I may have pulled off (not that I'll admit to an infraction of EPA laws), I've had to plug the vacuum port that I pulled evap lines off of or the carb then had a massive vacuum leak. Because of the unmetered air entering the system, the engine will run leaner than intended, robbing you of power driveablility. Try putting a vacuum cap over that port and see if things get better. You can buy them for pennies at any auto parts store.

Scott

Try changing out your line( fuel,vacuum line etc). If there is a crack that could account for the gas drip. I can't remember if there are 2 or 3 lines in there. Might have a crack in one of them. Mine crumbled when we redid all the lines a few months ago. Clear ones were the worst. My fuel tap didn't need replacing but since i had a new one we replaced it as well. That could be bad too. We have the same year scooter. What color is yours?Good luck

The evap port on the Vespa carb is not vacuum; it is atmospheric pressure. On the non-North American models, the same carb port is vented with a short hose elbow open to the atmosphere.

Then the dripping gas is the thing to focus on.

Scott

so i pulled the carb apart, cleaned it and put it back together. now it seems to run fine except that the power seems to be at about half of what it should be. the evap is still disconnected. im guessing the top speed is around 30.

i also just changed the spark plug as well to a cheapo generic one and am wondering if that could be it. thanks for all the help.

There seems to be an epidemic of this lately.

If you completely disassembled the carb, the likely suspect would be the rubber diaphragm that lifts the piston holding the needle valve. It is very tricky to re-seat it without leaks at the perimeter groove in the casting. Using silicone grease to help seal it has been recommended often here.

yea I made the same mistake with identical symptoms. take it apart again and fix the diaphragm.

so i took the black cap with the four screws off, greased up the diaphragm and put it back together. ( thats the piece you guys are talking about, right?) it did not seem to help, it still runs super slow. could
the spring get messed up when it goes in there?

you have to make sure that the diaphragm is seated in the ring in the metal. It cant just be greased and put in. If done properly grease is not necessary actually, just makes it slightly more easily.

The diaphragm will almost tuck into the ring.

you guy are great. getting a good seat on the diaphragm worked great. the scooter now runs like a dream.

someone asked about the color.. and it's yellow with a brown seat. i just got it for my girlfriend because some #$@%&! stole her hot pink et4 from in front of my house.

thanks again everyone.