J.P. Instruments EDM 760 Pilots Guide - Manual (Page 34)

Then tap the STEP button to complete the entry and advance to the
Manual indexing mode.
Adding Fuel and Auxiliary Tanks
If you either
a) added less than full fuel to only the main tanks, or
b) topped the main tanks but have some fuel remaining in the
auxiliary tanks,
then select FILL + and the next display will ask you how much you
added: .0 GAL (or selected units). Hold the LF button to count up, tap
the LF button to count down. The count up will stop at full tanks, since
you cannot add more fuel than would top the tanks.
If you added fuel to only the main tanks, then input how much you added.
If you topped the main tanks, but have some fuel remaining in the
auxiliary tanks, input how much is now in the auxiliary tanks.
You can “add” a negative amount of fuel if you remove fuel from the
aircraft or wish to correct the total quantity of fuel on board.
Accumulate Total—Trip Total
You may either display total fuel used since the last time you informed the
EDM-760 that the aircraft was refueled, or
for an extended trip with multiple fuel stops. This selection affects only
the
USD measurement. How to select whether to accumulate or reset is
described in “Pilot Programming” beginning on page 37.
Resetting “USED”
Every time you inform the EDM-760 that the aircraft is refueled, the
amount of fuel used is set to zero, unless the instrument is programmed to
accumulate. The display of fuel used pertains only to the fuel used since
the last time you informed the EDM-760 that the aircraft was refueled.
To reset to zero the amount of fuel used at any point in time, manually
step to display
USD and hold both buttons for five seconds until the
display shows . 0 USD.
Fuel Management
Without a means of measuring fuel flow, you must rely on the aircraft
fuel gauges or total time of flight. Aircraft fuel gauges are notoriously
Page 30 Engine Data Management