87 ranger fuel gauge

[ranger_redneck]

well, i finally got my truck running better than ever and getting pretty good mileage with it (hit 20 mpg last week)
now, one last issue that i would like to address.
my fuel gauge is a little weird.
if i fill, it reads full like it should, but the second i start driving it drops to a little under 3/4
then when i stop, it drops to E and goes back to full
i have a triple gauge pod that i will be using for (fuel pres. Volts. and fuel.)
i believe the sender is 73 ohms (empty) and -10? ohms (full) if someone could clarify that for me that would be wonderful.
thank you

 

[RonD]

Yes, those OHM levels should be correct for '87, Ford changed gauges and senders in '89

Good read here on Ford fuel gauges: http://www.fordification.com/tech/fuel-sending-units.htm.

The sending unit in the tank is a variable resistor, like a Light Dimmer, the resistance changes as you rotate the dimmer knob so light gets brighter or dimmer.
Sender has a float on the end of an arm and that moves the "dimmer" to more ohms or less ohms.

The gauge is the "bulb", needle goes up and down based on OHMs from sender in the tank.

Not sure if a bad sender can act the way you describe.

Might guess would be a gauge or wire issue.

 

[ranger_redneck]

i will definitely get a little more in detail with this before i go ahead and replace the gauge.
thank you for the info!