Two fuel senders in series

[davepl]

I was just thinking, since fuel level senders are ohm (resistance) based and higher ohms means more fuel, couldn't you in theory run the senders all in series, and it'd tell you what the total level of all three tanks was? If you had two half tanks, it'd read full. A quarter and an empty would read the quarter.

When all were full you'd have 270ohms and the gauge would read about 1/4 way past full, based on seeing it open in the past.

I imagine people either only monitor the main tank or, if fancy, have their switch also switch which sender to read. But on paper it'd seem to work.

[dutchmanz]

Your gauge should read 0-90 ohms. 90 being full. A dash mounted switch would be your easiest option. The senders in series would not work like you are suggesting without damaging your gauge. GM did use a module on the 3500HD trucks to average both tanks and send the correct value to the gauge. One could probably be used to do the same for your truck. It was only a 2 tank system tho.