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3 Reasons Not to Top Off Your Gas Tank

Even though the average American driver is used to filling up on gasoline every couple of weeks, that dreaded “E” always seems to pop up out of nowhere. You’re either sitting in your driveway wondering if you should break out a gas can or on the road praying that you make it to a gas station in time. No matter how stressful running on empty can be, there is typically enough fuel left in the reserve for the trip. When you do arrive, it’s understandable to want to fill that gas tank to the brim. So why not top it off when the pump shuts off? Here are 3 good reasons why you shouldn’t:

Accidental Spillage

Most fuel pumps at gas stations shut off automatically because they can sense when your tank is full. That means any additional gasoline could spill out onto the ground and even get on your person. How does it know when to stop fueling? A tube within the pump’s nozzle slowly releases air from a built-in diaphragm within the handle. As gasoline fills your vehicle’s tank, that tube eventually fills as well. When the tube is full, there is an immediate change of pressure within the nozzle and the air in the diaphragm is forced out. This causes the handle to click and shut off the flow of gas.

Potential Vehicle Damage

Imagine that you can see your vehicle’s gas tank with x-ray vision for a moment. The first thing you’d notice is that it is not completely full. That’s because it was designed to allow for the expansion of gasoline. Excess fuel has to go somewhere else then, like the vapor collection system. This system is meant to collect vapors from gas through a charcoal filter, ultimately preventing pollution. When gasoline is redirected here, it can weaken and eventually damage the entire system.

Paying it Forward

While your charcoal filter drowns as you continue to top off your tank, gasoline is then backed up into the pump’s own vapor recovery system. This system works to stop you from damaging your vehicle and even the pump itself. While it’s also meant for vapors, it will take in and store the excess gasoline back inside of its tank. Think of it like you’re unintentionally paying for the next person in line’s gas – except they still have to pay for what you paid for.

Express Mart Does the Work for You

The next time you visit your local gas station like an Express Mart, don’t think about how a fuller tank will somehow improve your gas mileage. After learning the information from above, you can see how it doesn’t work that way. Our pumps carefully monitor how much gasoline is pumped so that you don’t have to. Trust in us so that you can get back on the road knowing that you won’t have to run on “E” any longer.

Express Mart is owned and operated by HSO, fueling at 9 locations across Jefferson and Washington County. HSO is a supplier of bulk fuel, offering wholesale petroleum products through fuel delivery. We serve farms, construction sites, and businesses whenever they are in need. Call us today at 1-800-467-5044 to schedule a delivery!




6910 Front Street. Barnhart, Missouri 63012

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PO Box 9 Barnhart, Missouri 63012