Retail Motor Fuel Dispensers)
Complaints and Possible Explanations.



The points outlined in this article may be helpful in addressing complaints in which the consumer questions pump
accuracy based on the rated capacity of the vehicle's fuel tank, fuel tank indications, pump indications, printed
receipts etc... However, it is important to recognize that in some such instances there may actually be a problem
with pump accuracy or its manner of use. Consequently, it is our policy to thoroughly investigate all complaints
within 24 hours if possible in an attempt to determine the cause of the discrepancy.


1) The total price indicator was registering before I even started pumping gas...

This could be caused by a number of factors such as a malfunctioning nozzle, bad check valve, pressure
loss in the system, diagnostic system not being set up properly, pump not being used recently, temperature
variations, etc...

2) The pump gave me no fuel until after a few seconds and then it came on...

As soon as the nozzle is depressed, some systems goes into a diagnostic mode to check for abnormal
behavior delivering fuel at a lower pressure rate, as soon as the system thinks everything is alright it then goes in
high flow mode. This may take anywhere from 1/2 a second to 5 seconds to complete the diagnostic.

3) The total price per gallon on the street sign did not match the pump price...

This may be caused by electronic elements that are malfunctioning at the pump. More likely the manager of
the station raised the price on the pump before changing the sign. Managers are always told "when raising prices,
change the street sign first and when lowering prices, change the pump first." You should only pay for what the
pump states as the total price.

4) The price per gallon or the fuel grade on my receipt did not match what I bought at the pump...

This usually happens when a customer pays with a credit card in the store. The credit card machine
sometimes is not interfaced with the dispenser so it is up to the manager to input the correct price per gallon and
grade. As long as the total price is correct, the customer was not overcharged for their purchase.

5) The pump did not shut off and I was sprayed with fuel...

This sometimes happens when there are too many users of a particular grade causing low pressure in the
system which the automatic shut-off valve cannot detect (a major change in tank pressure when full) or the valve
malfunctions.

6) The dispenser was pumping real slow...

Dirty fuel filters in the dispenser are the usual cause although there are other reasons. At lower pressure
rates, the consumer usually gets more than they paid for.

7) I put 20 gallons of gas in my car and my owner's manual says I only have a 18 gallon tank...

This is our number one complaint. Often when fuel prices rise as they have during 2007, we see an increase
in the number of complaints related to the accuracy of gasoline pumps (retail motor-fuel dispensers). Frequently, we
receive consumer complaints from motorists who believe they filled their vehicle's fuel tank with more gasoline
than the tank is specified to hold. The possibility that the pump may be inaccurate exists, but typically complaints
arise because the vehicle tank capacity rating is only an approximate volume. The following are some possible
reasons why a motorist might see variations in tank capacity indications.



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Fuel Tank Capacity and Gas Pump Accuracy


Rated vs. Actual Fuel Tank Capacity

The vehicle's fuel tank capacity rating is a reasonable approximation given variables such as differences in
design practices, test procedures, and other influence factors on the fuel system. Some manufacturers estimate that
fuel tank capacity can vary by as much as 3 % from the actual tank capacity as a result of normal variations in
design characteristics, the manufacturing process, and other inherent factors such as the physics associated with
components and the electronics in the fuel system and fuel level indications. Knowing the vehicle's fuel tank
capacity provides the driver with information needed to plan driving distance, refueling stops, fuel costs, etc.,
associated with highway travel.

Tank capacity is also a factor used by vehicle components that monitor emissions and other on-board
diagnostic equipment that affect fuel level indications. Typically, the owner's manual provides a reasonable
estimate of the vehicle's fuel tank capacity. Some owners manuals list fuel tank capacity in SI (metric) units,
equivalent U.S. customary units, as well as other international units of measurement such as the British Imperial
gallon, for example, 70 L (18.5 gal, 15.4 Imp gal). The tank capacity's numerical value is reported in tenth of whole
figures rounded to the nearest value and, therefore, represents an approximate volume.

Various related terms are used by auto manufacturers and associated agencies to describe the actual (liquid-
and vapor-space) and advertised fuel tank capacity and fuel levels important to drivers. In March 2005 the Society
of Automotive Engineers (SAE) Refueling Interface Subcommittee published SAE J398, a guide that clarifies
terminology as well as a procedure for establishing fuel tank capacity for passenger vehicles. In SAE J398, the
vehicle's fuel tank capacity rating is reported as an average volume based on test data gathered on the capacity of
multiple tanks. Representative samples of a particular type of fuel tank are filled to a prescribed number of
automatic shut-offs by the pump nozzle to determine fuel tank capacity. Attempts by drivers to fill the fuel tank
beyond the pump's automatic shut-off point can result in fuel being drawn into the pump's or vehicle's vapor
recovery systems. Auto manufacturers choose the test conditions and may vary the test mode based on the intended
use of the vehicle.


Drivers might find that a vehicle's fuel tank capacity rating includes only the usable portion of the tank's
liquid capacity shown in the diagram below or both the usable and un</i>usable portion of the tank's liquid capacity.

The un</i>usable volume is the portion of the fuel tank's liquid capacity that lies at the bottom of the tank out of
reach of the fuel pump. The usable volume is the portion of the fuel tank's liquid capacity that can be delivered
through the filler pipe into the tank when the vehicle is level (and when the un</i>usable volume is also in the tank).
The vehicle's fuel tank capacity does not include the vapor headspace (that portion of the tank compartment at a
level above the filler pipe neck) or the volume of the filler pipe. Sometimes drivers ignore the pump nozzle's
automatic shut-off and continue to hold the nozzle operating the lever open in an attempt to deliver additional fuel.
When this happens, the additional fuel begins to fill the vapor headspace and the filler pipe that are not considered
part of the tank's rated capacity, thus resulting in a delivery of fuel greater than the fuel tank capacity rating stated
in the owner's manual. Similarly, the lanes that surround the service station pumps may not be level and fuel may
shift into the vapor space thus allowing more fuel to be delivered into the tank.

Indicated Volume

Another scenario that can prompt consumer complaints involves the fuel tank capacity and the fuel gauge
indication. When the fuel tank indicates a particular level, the customer frequently assumes that this represents a
corresponding fraction of the fuel tank capacity. For example, on a fuel tank with an 18-gallon rating in the owner's
manual, the consumer assumes that a "half-full" fuel gauge indication means that 9 gallons of fuel remains in the
tank. When the consumer is able to dispense more than 9 gallons of fuel into that "half-full" tank, the consumer
assumes that there is a total of more than 18-gallons of fuel in the tank, thus exceeding the fuel tank rating listed in
the owner's manual. The consumer then concludes that the gasoline dispenser must be in error and lodges a
complaint. -3-



Passenger Vehicle Fuel Tank Capacity
Note: The diagram illustrates the parts of a fuel tank that relate to tank capacity.
The dimensions do not represent the exact scale of each tank component.


In addition to considering the factors discussed earlier regarding fuel tank capacity, it is important to
understand that manufacturers also take into account a number of factors when designing the fuel indications. Many
variables have an affect on a vehicle's analog and/or digital fuel level indications. Auto manufacturers design fuel
systems with gauges, lights, audible signals, and/or other indications to provide advance warning to the driver when
fuel levels are low and warrant attention. Motorists would find it inconvenient if the fuel gauge needle pointed to
"Empty" or the low fuel indicator light was designed to illuminate at the very moment the tank runs out of gas, not
to mention the possible adverse affects to the vehicle's fuel system. In fact, some owner's manuals recommend
maintaining a minimum level of fuel.

A shift in fuel levels may occur when the vehicle is not on level ground, for example, when parked on a hill
or traveling around a curve. A temporary change in the position of fuel can cause the fuel gauge needle to shift
and/or cause the low fuel warning light to flicker or give the appearance of more or less fuel in the tank than is
indicated by the fuel gauge. Drivers should also keep in mind that the indicated fuel