PGO Big Max Scooter- Losing Gas When Not In Use/ Parked?

[airplanes5]

Hi everyone,

I am new to this site and forums so please go easy on me, any help you can provide would be great. To start, I am not to mechanically inclined and do not know as much of the lingo as I would like to, but will do the best I can.

This past October I purchased a used 2005 PGO Big Max 50cc scooter and am loving it. When I first purchased it, I was having all sorts of problems since the guy who I bought it from changed things around (disconnected fuel line, hard cold starts, kick start jammed etc). I knew this going into it but it was so cheap I had to take it.

I took it to a local scooter shop and they did a great job cleaning it all up and making it work well. All it needed was a carb clean, some kick start grease, oil pump reconnect, etc...small stuff. Now I am having a problem that I can definitely not figure out.

I have the scooter on my college campus and do not drive it everyday. Last Friday I filled the scooter up with a full tank and parked it. One week later I come back, turn the scooter on, and the gas gauge read empty. I didn't see any puddles of gas or leaks anywhere. I physically looked in the tank and it was certainly lower than what it was before, I would say 1/4 full but its hard for me to tell how deep the tank goes. That same day I went back to the gas station filled it up (the gas gauge said full and I could physically see it at the top) and put the gas cap on. Interestingly, the tank only took about .5 gallons, even though it is a 1.1 gallon tank I think.

4 days later I came back, started it up, and the gauge reads half full. Again, no puddles or physical leaks. Opened it up, and sure enough it looked half full. I called up the scooter shop and told the mechanic. He has no idea what it could be. While servicing it he said he fixed all leaks and problems. Now we are looking into a new fuel tank, he thinks maybe some rust problem somewhere? But he wants to look at it again first.

Could this be just gas evaporating? Maybe I have a bad gas cap which isn't closing tight enough? Is that possible? In the off chance this could be true, maybe someone is stealing my gas. But I think that would be hard since the gas cap requires my key to open. He said I can bring it down and he will take a look, but how does gas just disappear in a matter of days.

Any advice you all can give would be so appreciated. Again, I am not to good with the mechanic jargon but think I understand the basics. Thank you everyone!

[teddy554]

got me stumped...

[90GTVert]

to the forum.

Are you sure you aren't riding in your sleep?

Hopefully not. lol For one thing, the fuel gauges are not always accurate and the shape of the tank can make it tough to get a good linear reading. Sounds like you're on E at basically half a tank. There's a chance that you could remove the pickup from the tank and reposition it (I think ppl have found them installed wrong) or possibly bend it in a manner that would allow it to go lower in the tank if there's enough travel for it to still reach the top. I just learn my gas mileage and use the odometer to know when to fill up.

I have had a float issue with a carb where it would leak very slowly. Most of the time the only reason I realized it leaked was from an oil puddle. I pre-mixed oil into my gas. Even though the gas would evaporate quickly on the ground in such small amounts, the oil would not. It may have even been an intermittent leak. Not sure, I could never see it leak, only see the oil residue directly under the overlow from the carb. Perhaps you could have something like that going on and with your narrow range of motion on the fuel gauge it looks like you're losing even more than you are?

I could see that scenario working for evaporation perhaps. I couldn't see it evaporating that quickly while in the tank. The surface area to volume ratio is much different when dealing with a tank full vs a drop.