[MrE]

The newer technology senders require more than one wire to the gauge. Our existing setups are two wire, but one of the wires is ground and is attached to the frame near the sender. The point is that running additional wire from the fuel tank to the cockpit would be required. Then of course, you have to have a gauge that is compatible with the new sender. All of these are achievable, but work and cost involved in pulling this off.

The only extra wire required is a switched +12v power that doesn't need to come from the cockpit. The following is from 19-250.pdf

Sender Wiring

1) Connect a good ground to the stud on the sender labeled
“GND”.
2) Connect a switched +12V power to the stud on the sender
labeled “+12V”.
3) Connect the fuel gauge’s signal wire/stud to the stud on the
sender labeled “Gauge”.

Sender / Gauge Calibration

Averaging Switch Settings
ON - ON: Minimum averaging with fastest response. (Helpful when bench testing)
ON - OFF: Short averaging.
OFF - ON: Medium averaging.
OFF - OFF: Long / normal averaging with longest response.
The correct averaging setting depends on the fuel tank size and volume. Normally, using a long average setting will
make readings smooth, but may update slowly when fuel level changes. In reality, fuel level change is very slow, so the long / normal averaging setting is recommended.
Calibration Steps
You don’t have to calibrate all settings. Each calibration setting can be set independently. For example, if you change to
a new gauge, you only need to calibrate the gauge settings, the tank low and full settings are still good. You can also calibrate
the gauge without the fuel tank and calibrate the fuel level without the gauge.
Press and hold P1 until the slow flashing green status LED turns off, then release the button to enter the calibration
mode.
Standard Gauge Calibration (short sweep)
1) Gauge Empty Position:
a. The LED should be solid blue. Press P2 or P3 to move the gauge pointer to empty. If the pointer is initially
above full or below empty, you may need to keep holding P2 or P3 for up to 8 seconds before you see the
pointer move.
b. When the pointer is positioned to empty, press and hold P1 until the LED turns off. Then, release the button.
The LED will flash red 3 times to confirm the new setting is saved. If the LED doesn’t flash red 3 times, the
new setting is NOT saved.
NOTE: If you only momentarily press P1, the current setting won’t be saved, and you will skip to the next setting.
2) Gauge ½ Position:
a. The LED should be solid green. Press P2 or P3 to move the gauge pointer to ½. If the pointer is initially
above or full or below empty, you may need to keep holding P2 or P3 for up to 8 seconds before you see the
pointer move.
b. When the pointer is positioned to 1/2, press and hold P1 until the LED turns off. Then, release the button.
The LED will flash red 3 times to confirm the new setting is saved. If the LED doesn’t flash red 3 times, the
new setting is NOT saved.
NOTE: If you only momentarily press P1, the current setting won’t be saved, and you will skip to the next setting.
3) Gauge Full Position:
a. The LED should be solid red. Press P2 or P3 to move the gauge pointer to full. If the pointer is initially
above or full or below empty, you may need to keep holding P2 or P3 for up to 8 seconds before you see the
pointer move.
b. When the pointer is positioned to full, press and hold P1 until the LED turns off. Then, release the button.
The LED will flash red 3 times to confirm the new setting is saved. If the LED doesn’t flash red 3 times, the
new setting is NOT saved.
NOTE: If you only momentarily press P1, the current setting won’t be saved, and you will skip to the next setting.
P1 P2 P3 GND +12V Gauge
Averaging Setting Switches
Status LED Calibration Buttons
Classic Instruments Full Sweep & Programmable Fuel Gauge Calibration
Set the fuel gauge to operate with a standard universal (240-33Ω) sending unit. Make sure the gauge is powered and
connected to the fuel sender.
1a) Gauge Empty Position:
a. The LED should be solid blue. Connect a DC voltmeter to read the voltage on the “gauge” post of the
sender. Press P2 or P3 to adjust the voltage to 2.69V.
b. When you have the required voltage, press and hold P1 until the LED turns off. Then, release the button.
The LED will flash red 3 times to confirm the new setting is saved. If the LED doesn’t flash red 3 times, the
new setting is NOT saved.
NOTE: If you only momentarily press P1, the current setting won’t be saved, and you will skip to the next setting.
2a) Gauge ½ Position:
a. The LED should be solid green. Connect a DC voltmeter to read the voltage on the “gauge” post of the
sender. Press P2 or P3 to adjust the voltage to 1.66V.
b. When you have the required voltage, press and hold P1 until the LED turns off. Then, release the button.
The LED will flash red 3 times to confirm the new setting is saved. If the LED doesn’t flash red 3 times, the
new setting is NOT saved.
NOTE: If you only momentarily press P1, the current setting won’t be saved, and you will skip to the next setting.
3a) Gauge Full Position:
a. The LED should be solid red. Connect a DC voltmeter to read the voltage on the “gauge” post of the sender.
Press P2 or P3 to adjust the voltage to 0.63V.
b. When you have the required voltage, press and hold P1 until the LED turns off. Then, release the button.
The LED will flash red 3 times to confirm the new setting is saved. If the LED doesn’t flash red 3 times, the
new setting is NOT saved.
NOTE: If you only momentarily press P1, the current setting won’t be saved, and you will skip to the next setting.
Tank Calibration
4) Tank Empty Position:
a. This calibration is to set the tank empty (away from sender) level.
The LED should be flashing green.
b. Set up a flat target and sensor parallel to each other on a table.
Set the distance between them equal to the depth of your tank
minus a small reserve distance (1/2” reserve is typical). The LED
will flash faster the closer the target is to the sender.
c. Once the correct distance is set, wait at least 10 seconds to make
sure the sender’s reading is stable.
d. Press and hold P1 until the LED turns off. Then, release the
button. The LED will flash red 3 times to confirm the new setting is
saved. If the LED doesn’t flash red 3 times, the new setting is
NOT saved.
NOTE: If you only momentarily press P1, the current setting won’t be
saved, and you will skip to the next setting.
5) Tank Full Position:
a. This calibration is to set the tank full (near sender) level. The LED
should be flashing blue.
b. Set up a flat target and sensor parallel to each other on a table.
Set the distance between them equal to the distance between the
bottom of the sender and the full fuel level + ¼”. The LED will
flash faster the closer the target is to the sender.
c. Once the correct distance is set, wait at least 10 seconds to make
sure the sender’s reading is stable.
d. Press and hold P1 until the LED turns off. Then release the
button. The LED will flash red 3 times to confirm the new setting is
saved. If the LED doesn’t flash red 3 times, the new setting is
NOT saved.
NOTE: If you only momentarily press P1, the current setting won’t be
saved, and you will exit the calibration. The status LED will return to a slow green flash.