Troubleshooting fuel gauge w/frame mount tank

[DjangoFett]

I recently bought a '71 SWB with the cab tank removed and has what I'm told is an '06 Crown Vic 19 gallon between the rear frame rails. The factory gauge reads accurately at "full", but shows "empty" with somewhere around 7 gallons still left in the tank. I didn't do the tank transplant myself, but presumably the factory sending unit was left in place. What would everyone suggest to try to correct this? At this point it's just a minor inconvenience, but as we start to drive the truck more, it would be nice to know how much gas is actually left in the tank

[basketcase0302]

="DjangoFett" I recently bought a '71 SWB with the cab tank removed and has what I'm told is an '06 Crown Vic 19 gallon between the rear frame rails. The factory gauge reads accurately at "full", but shows "empty" with somewhere around 7 gallons still left in the tank. I didn't do the tank transplant myself, but presumably the factory sending unit was left in place. What would everyone suggest to try to correct this? At this point it's just a minor inconvenience, but as we start to drive the truck more, it would be nice to know how much gas is actually left in the tank

You're probably not gonna like the answer to this question. Both fuel gauge and sending unit have OHM values that have to match, (typically they are "paired" or matched in OHM values from the factory or supplier). Not 100% sure but am guessing you'll have to graft a CV fuel gauge into the bump instrument panel now?

Here's the fuel tank / gauge tech that might help some:

http://www.fordification.com/tech/fueltank01.htm

[DjangoFett]

Thanks Jeff!
While I don't know how feasible grafting a CV gauge into the existing dash cluster, it mat be worth investigating. When we get to the interior, we may replace the gauge cluster with an F600 insert with VDO gauges, or even a whole aftermarket setup (I haven't been told what we're doing yet - I actually bought the truck for my wife!), so conceivably I could correct it then. But in the mean time, I was hoping for a somewhat-painless fix

[basketcase0302]

Robert,
YW and try running a search here on gas gauge "replacement" or other key words. I've seen more than one member here do the grafting of the fuel gauge before. It was done using the dial and "guts" of the donor gauge panel, (would be the CV in your circumstance) and the bump panel "inlay" (if that word is correct for the gauge panel itself).
Maybe also doing a little more research on the ohm values of each gauge, (CV / F-600 / bump era) would help you with your answer.
I want to say 21 ohms rings a bell for the bump gauge but not positive on that either.