Datsun Roadster Forum-311s.org

The fuel gauge on my 69 1600 reads full when I top the tank. But by 100 miles driven it has progressed to the empty line when in reality it’s probably closer to a half a tank. Any recommendations on fixing its functionality?


Thanks

Clean the connections at the tank.
Also check the OHMs full should be 86 and empty 10 or the other way round.

fj20spl311 wrote: ↑Tue Jun 26, 2018 6:41 pm Clean the connections at the tank.
Also check the OHMs full should be 86 and empty 10 or the other way round.

since at infinite impedance (resistance) there is no current flow and my gauge reads empty when off, the 86 ohms is empty. Pretty easy to check the resistance of the gauge sender when you think it's half full.

Disconnect battery (a precaution may not need too), take plate off the tank remove wires from the sender. Measure resistance across the sender. If it's close to 80 ohms then it's faulty and or needs a good cleaning. You can take it out and measure the resistance as you swing it from stop to stop too and see if a cleaning of the armature might help it.

Maybe you only get 10 mpg?

I had same problem on 1967.5 2000. Problem was a bad voltage reducer that supplies the gauges. My temp fix was to shorten a wine cork to expand the tabs the wires connect to. Proper fix is a new voltage reducer. You'll find the reducer under the dash, along side the steering column. Test by expanding the wire connections with your hand while watching the fuel gauge. Replacements are available from Rallye and DatsunParts.com.