Cortina MK1 fuel sender.

[1970 cortina GT]

Tried reversing polarity, checked all the grounds, still no change. One thing you mentioned stirred my curiosity Pete, ‘ staying too long on 0 volts and too short on 5 volts ‘ . The instruction leaflet that I got with the v/s mentions that it gives a constant 5 volts? When I check with a meter I can confirm that. V/s was bought from the MK1 owners club so I presume it is correct.

[peteleo]

This new type of v/s from the club produces a constant 5 volts output regardless of varying input voltage from the battery keeping the meter steady. Replacing the old type pulsating 0-5 volts v/s.

Try applying 12 volts directly to the fuel gauge ( by-pass the v/s ) move the sender arm full to empty. Do this for just a short time to see if the fuel gauge goes to full.

[1970 cortina GT]

I’ve put it all back together again, I still try and use it as a daily driver. I’m sure everyone is tired of my issue anyway. I’ll look again during the winter when it’s off the road, I’ll check your suggestion then Pete. Thanks all.

[Dave A]

ground is what makes the guage go up.

run a temporary ground right to the sender body itself not just the tank to verify the issue.

also disconnect the wire at the sender, ground it and turn on the key the guage should go to full. do not leave connected to ground for more than the time it takes to do this


the sender just varies the resistance to ground, less resistance the higher the guage reading.

[Dave A]

ground is what makes the guage go up.

run a temporary ground right to the sender body itself not just the tank to verify the issue.

also disconnect the wire at the sender, ground it and turn on the key the guage should go to full. do not leave connected to ground for more than the time it takes to do this


the sender just varies the resistance to ground, less resistance the higher the guage reading.