New square body Owner Questions
 

Dual tank 78 scottsdale, seems like the gas gauge is not working properly. I put gas in and it moves some and then goes down like on empty. What should i look at first . Any suggestions would be appreciated. Will have more questions as i go through the truck and discover any more small issues. I'm general truck is in great shape . Thank you

Re: New square body Owner Questions
 

This could be similar to the issue I had. Check out the video.

https://www.youtube.com/watch?v=HuGfmgNPTS0

Re: New square body Owner Questions
 

Same behavior on both tanks?

If both do the same, then suspect the gauge or cluster wiring. If one works proper and one weird, suspect switch, sender or wires between switch and sender.

Re: New square body Owner Questions
 

Empty with more than 7 gallons of fuel in the tank usually means you have a shorted sender wire or bad sender.
If you have less than 4-5 gallons in the tank I would not expect the needle to move off empty.

Dead short to ground on the signal wire will drive the needle to E.

90Ω resistance to ground on the sender wire will drive the needle to F.

If you unplug the sender or break the tank ground wire the needle will go to the 3:00 position.