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Fixing the Fuel Gauge on a John Deere 1020

posted Apr 20, 2010, 11:01 AM by Matt Francis   [ updated Apr 21, 2010, 8:35 AM ]
Well, this spring I finally decided to tackle the only electrical problems on my old JD 1020.  As an electrical engineer, it was simply a matter of pride!

First, the gas gauge has never worked on the old girl.  And, of course, the tractor always runs out of gas at the farthest point from the barn!  To begin, I was able to determine, using an ohmmeter, that the sender was working and on this model has a range of 0-30 Ohms.  A gas gauge is basically an ammeter that measures the current through a variable resistor.  The sender is a variable resistor, the resistance of which changes based on the level of fuel.  The sender below is out of my old BMW 320i, but is representative of what's on the tractor.

A little research led me to learn that a 0-30 Ohm setup was common on GM products before '65.  After '65, everyone switched to something more like 270-90 Ohm setups, which are far less prone to corroded connections and the like.  So, rather than shell out $100 for a JD gauge, I ordered this, an Auto Meter 1318, for about $35.  As a bonus, its extra sporty and gives my tractor some real muscle car feel ;)

The only mod I had to perform was to change to "blade" connectors and to add a ground wire (since the new gauge had a plastic housing).   So, now if I run out of gas, it's my own darn fault!