Ask SF: How to Not Over-fill a Vespa’s Gas Tank

Today’s Ask ScooterFile question comes to us from Craig:

I love my Vespa. Sure it was a little expensive but luckily, I was able afford it. I have a little complaint though. I can’t fill the gas tank without spilling gas all over the inside of the “luggage compartment!” Surely, I’m not the only one this is happening to. Is there some secret I’m not ware of? The filler neck is just large enough for the hose nozzle to fit so I can’t see when the fuel level is nearly full.

Thanks for writing in, Craig. I know this issue all too well myself. As a former Vespa GT200L owner, I too struggled with over-filling the fuel system back when I still owned that scooter. Overfilling a Vespa has more than one downside, actually. Spilling fuel into the under-seat storage compartment is bad enough, but over-filling can also lead to issues with your fuel evaporation capture system. If you’ve ever over-filled, then had hot start issues, chances are the fuel evap system is the culprit.

The problems are well known, so how about some solutions? I have a few pieces of advice for you.

1. Fuel up more slowly
Standard gas station fuel pump handles have a progressive trigger. Instead of fueling at full pour, pull on the trigger enough to get the flow of fuel started, and then you’ll find you can actually back off a little bit and have a lot more control. It’ll take longer, but we’re only talking a couple gallons here. Be patient and you’ll make fewer messes.

2. Use your ears
Next time you fill up, listen to the sound coming out of your fuel tank. Because fuel is displacing air, there’s an effect that’s similar to blowing across the top of a soda bottle that still has some liquid in it. The tank will actually whistle a little bit, albeit at a very low note. If you listen for this, you’ll not only hear it, but you’ll hear it change as you fill up.

The less air remains in the tank, the higher pitched that sound becomes. For most of your fill up it’ll sound more or less the same — like a humming hiss. Right toward the end though, as the fuel level starts getting a lot closer to top of the tank and starts coming up the neck of the tank, the sound will quickly get more high pitched. Listen for this sharp change in pitch and then simply stop fueling. Your tank is full at this point, only the neck is empty, so you should be good to go.

3. Fill from the very top
Place the nozzle of the gas pump as close to the top of your tank as possible rather than all the way down in the neck of the tank. You can then use short, controlled bursts to fill the tank, watching between bursts for the bubbly surface of the fuel level. It requires visual monitoring, but it also helps to prevent spillover. (Special thanks to ScooterFile Editor and Vespa owner Miccah Duckett for contributing this suggestion.)

4. Stop trying to “fill” your tank to the absolute top
Part of what makes suggestion #2 work is to let go of the compulsion to get every last drop of fuel into the bike. You just don’t need to. Unless you’re setting out across the desert, squeezing every last drop of fuel into your tank doesn’t actually serve a purpose other than a false sense of efficiency. I get it. We all do it. It feels right, but resist the impulse. Instead of trying to “fill” your tank, change your mindset to something more like “adding fuel” instead. You don’t need all the fuel, you just need more than you currently have.

5. Standardize your fill-ups as best you can
Chances are you’re getting pretty consistent mileage out of your Vespa. So between the odometer and the fuel pump, you should be able to standardize your fill ups a little bit. Keep notes for a little while, if you don’t already, and figure out a pattern you can use to standardize your fueling. If 100 miles on the odometer uses approximately 1.25 gallons of fuel, then try to go 100 miles between fuel stops and use the gas pump meter to put in exactly 1.25 gallons each time. Eventually you’ll get a little bit behind or a little bit ahead, but most of the time this method should prevent over-filling because you’re not really trying to fill up. You’re just adding fuel to replace what you’ve used.

Let’s here from the community.

Have a better tip? Let’s see it in the comments below.

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  • I can certainly attest to the frustration of having fuel flow out of the neck and into the carrier. Tips are good. One additional one that almost always works flawlessly for me unless I rush. Put the gas nozzle into the filler with the control over the compartment — sort of like you are filling facing the rear of the scooter. I can fill the first half gallon pretty fast (knowing that the tank is low) and then slow the input speed. The automatic kickoff at nearly all the stations I frequent work fine in this configuration. The only time I get spillage is if I run the gas in too quickly. Shutoff still works but there’s just too much fuel still flowing with not enough room for it.

    I run my fuel stops by miles. Set odometer at zero after a fill up — refill at 60 to 70 miles. Usually takes about a gallon. Makes life predictable and easy and no fuel on my stuff in the compartment.

  • camsail

    Good tips on a common problem… one additional is simply lift out the seat storage bin and set it aside till done fueling.