Make sure you get all the fuel you pay for when filling up - Fuel Economy, Hypermiling, EcoModding News and Forum

jdub · 08-30-2008, 10:34 PM

I was just thinking about this practice the other day as I was filling up and realized that I hadn't heard of anyone else doing it or sharing it so I thought I would contribute it.

Whenever you fill up your vehicle and the hose trigger shuts off to prevent backsplash, if you put the nozzle in the pump and end the fill up, you are leaving in some cases over half a cup of fuel you paid for in the nozzle hose.

Pumps typically use a door with a switch that is activated by the nozzle end that goes in the tank to know when the nozzle head is placed back in the pump. This switch, when triggered instructs the pump to shut down and end the fueling session. If instead of putting the pump nozzle back in the pump, if you trigger the door by hand and then pull the trigger after this door has deactivated the session, in nearly every case the pump will allow you one more pull of the trigger to dispense the last little bit of fuel to clear the line/nozzle from your fill up. (Some older pumps actually have a manually operated lever that is engaged/disengaged by the user instead of the door, but the principle on pulling the trigger after activating the door or the lever/switch is the same).

This is fuel in the nozzle that you have paid for, but most people never do the extra pull because of the nature of the door and how its activated, so unless you manually trip the door by hand and leave the nozzle in the filler for the last pull, you are leaving that last little bit of gas at the station instead of dispensing it in your tank.

While half a cup of fuel does not seem like much, over 32 fill-ups it equals a an extra gallon of gas...

Try it next time you fill up and get every drop of what you are paying for.

Frank Lee · 08-31-2008, 12:39 AM

Don't you always get the previous guys' half a cup?

jdub · 08-31-2008, 12:44 AM

because I would be getting the previous person's half a cup and mine at the end of the fill up by flipping the door by hand and taking the pull too.

I have never tested pulling an unactivated nozzle from the pump and trying to pull the handle to get the extra half-cup before turning on the pump with my credit card. I suppose its something to test on the next fill up.

Frank Lee · 08-31-2008, 12:48 AM

If I get the previous guys' half a cup, am I not getting all the gas I paid for?

FastPlastic · 08-31-2008, 01:01 AM

Won't that throw off your MPG calculations? Seeing as it's not measuring that extra half cup?

groar · 08-31-2008, 04:22 AM

Quote:

Originally Posted by FastPlastic

Won't that throw off your MPG calculations? Seeing as it's not measuring that extra half cup?

1/32 gallon for a 10 gallons tank is 0.3%. Isn't it under the current error ?

Denis.

jdub · 08-31-2008, 09:59 AM

Quote:

Originally Posted by Frank Lee

If I get the previous guys' half a cup, am I not getting all the gas I paid for?

It depends on how the pump works and how it allows flowback to prevent spillage of that last little bit of fuel from your fill up. If the valve on the nozzle allows that undispensed fuel back into the holding tank then you don't get the previous guys half a cup. Like I said, I haven't tested trying to pull the handle on an unactivated nozzle to see if the last guy's half a cup is still sitting in there or not. I need to test to see what happens on next fill up, but my theory would be that the check valve on the line somehow lets that undisepensed fuel back into the tank to prevent someone from splashing fuel from an unactivated nozzle and creating a dangerous situation. Anyone that needs to fill up soon can report back, I am on a full tank and it will be over a week before I can test this out and report back

Also, it depends on whether you consider that extra half a cup in the nozzle after you shut the fuel pump off yours or the next guys. In my case, I consider it mine so I take it. Because of this, you are not getting all the fuel you paid for.

jdub · 09-01-2008, 04:19 PM

And a pump that has been sitting a while in the off state will not dispense the previous person's left over fuel after pump shut off.

The station I tested at was a QuikTrip in far North Dallas, and admittedly its a data point of 1 at this point, but it lends to the theory that the pump/valves allow the leftover fuel back into the line/tank somehow after some period of time.

This means that if you don't take your pull after pump shutoff, you are leaving that fuel at the station.