I was under the impression that the 4 pot cars had 12 gallons and 8 pot had 15. I might have made that up
Not joking about precision. Mine stays at "full" for a long time then gradually falls to half way, then plummets to zero. I can only assume it becomes very non-linear due to wear. We really need the reserve tap to judge when to fuel.Hi, Because of space constraints the tanks are the same height but the later 4 cyl and v8 tanks are fatter than the early 4 cyl. So the senders indicate level and are also not precision instruments as Harvey points out on numerous occasions.
Colin
I think you'll find that 2000 is 12 gal, and 2200 and V8 are 15.
Not joking about precision. Mine stays at "full" for a long time then gradually falls to half way, then plummets to zero. I can only assume it becomes very non-linear due to wear. We really need the reserve tap to judge when to fuel.
Here is a photo of the wire wound rheostat that is the basis of the sender unit for a 12 gal tank. The upper right terminal on the rheostat is connected to the instrument terminal and the lower left is connected to earth. The wiper terminal on the float arm basically shorts the wire windings to earth depending on the level of the float. With a full tank, the rheostat is almost completely earthed generating minimum resistance at the instrument terminal At minimum tank level, the full resistance of the rheostat windings is generated at the instrument connection. As you can see in the photo, the windings are much shorter when the tank is close to full, gradually getting longer as the tank empties and then reaching a constant length as the tank gets close to empty. A change in level close to full generates a much smaller change in resistance than the same change in level when the tank is near empty. Although far from being a precision instrument, the variation in the rheostat windings provides some compensation for the shape of the tank at various levels. I have never opened a 15 gal tank sender for comparison purposes but expect that the shape of the rheostat might be slightly different to reflect the difference in tank shape but having the same height.Hi, It's to do with the shape of the tank because there is less fuel in the bottom portion of the tank.
Colin