Gas in Vacuum Lines?
 

Hey everyone, first post here but love this site (has helped me a lot over the years).

I have my Motobravo Phantom GTX 150cc scooter that I'm having some troubles with. I can kick start it up, and it runs and I even rode it around the block. Next day I kick start it up, and the slightest twist of the throttle kills it. (If I wait a week or more, it will then give me 1 ride before repeating issue).

Did some looking, and I noticed there's liquid in the vacuum lines (most notably from intake manifold to the "T", and also the hose from carb. Seems to be sucking gas out of the carb?

Video showing liquid in vacuum lines (let me know if this doesn't work) --> https://goo.gl/photos/M4AaL1YXhxBSKP7W9

I already did a valve adjustment and carb clean before noticing this. Also replaced petcock after noticing this because I read that was sometimes a problem, but alas, this did not fix it.

Any known reasons for there being gas in vacuum lines like this?

Very nice video.......I would say the diaphram in air cut valve, must be shot. That's the only way I can see fuel being sucked out of there.

This link may help you understand that area of the carb.....http://scooterrebels.proboards.com/thread/967

Thanks rks, I'll have to check that when I get back in town tomorrow (also, good info, I didn't know about this part). If it is a torn diaphragm, will I just need to buy a new carb, you think? I can't seem to find any air cut valve diaphragms online

Probably the best way to go. The diaphragm kits are available for larger, motorcycle carbs, but they cost nearly as much as a complete, new, GY6 24mm carburetor.....which are readily available in the $20 - $25 range, including shipping.

You could remove the vac line to the valve, place a vacuum cap on the valve, and another on the 'T'....as a temporary patch. You would probably get a little backfiring, or farting when decelerating, depending on how quickly you shut the throttle down.....but it would be rideable until carb was replaced.

Thanks, new carb being ordered now. You were right, the cut valve diaphragm was indeed torn.

I did the temporary patch you recommended and got the scoot running. Took a lap around the block even. It did die while idling after I got it back in the garage but we'll see if new carb fixes that. I'll let you know though. Thanks!

New carb is in. No more gas in the cut valve vac line. I did notice some drops in the 2 vac lines coming from the intake manifold after I got it started (it then proceeded to die on idle).

Do you think there is a deeper problem? Or is it normal to have some condensation in those lines (I just recently got clear lines on those 2 so not sure what it used to do)?

I'm thinking there is still some issue somewhere, as it doesn't stay running if I can get it started. It dies on idle

Sounds like a simple adjustment to me. Loads of instructions are available.....type "gy6 carb adjustment", into any search engine.

Just go easy when turning the idle mixture screw in, a very lite touch/seat is all that's needed.

awesome thanks. I seem to be having trouble keeping it running long enough to really adjust anything. I'll keep trial and error with it.

One question though, there seems to be a lot of air coming from the hole above where the spark plug coil goes in. is that normal? (see the 2 pics here https://goo.gl/photos/M4AaL1YXhxBSKP7W9)

Thanks!

That's just air from the cooling fan finding it's way out from under the engine shroud....nothing to worry about.

It may be just the camera angle in your photos...... but it looks like the carburetor is not properly seated in the intake manifold. An air leak there would give you fits.