Fuel sender and gas gauge in ‘63 and ‘64 Darts.

[panoply]

On my two Darts, the gas gauges work but both prematurely retreat down below the empty line. They pretty much lay at empty after 100 miles or 7-8 gallons, so I know there’s 10 gal more to go. Then the needle will eventually lay down below the empty line and At that point, I’ve determined, that they actually are still holding 4 gallons in the tank.
Is this common? Any ideas.
Thanks

 

[RustyRatRod]

Could be if the float is compromised.

 

[Jim Kueneman]

Is it an aftermarket sending unit? If so, it’s probably a little short arm piece of junk. Get the A100 sending unit that vans auto is making at least that has the long arm which helps a lot, but it still doesn’t have the progressively wound resistance. You’ll probably have to bend the arm a little bit to make it empty when it’s truly empty, but it works way better than those little short arms that are being sold as replacements.

 

[panoply]

That sounds like good insider info. Thanks, Jim.

 

[bcschief]

I would try to save the original sender unless it's bad, I would remove it and test it and if it is good I would replace the sock and the float. The brass float is still available from most Ford resto vendors if you can't find one from a Mopar vendor. I would also check the IVR and make sure it's operating within spec, and I would also drop and clean the tank, so you don't have issues with a dirty tank.