New-to-me 77 F250 Camper Special
 

I just recently traded for a 1977 F250 Camper special. This is my FIRST Ford which I'm kind of leery about. So far, the truck doesn't want to start and it doesn't hold a charge once it gets jumped. The first day I got it, I put in 7 gallons of gas and with it idling for only 5 minutes, it was right at empty. I supposedly had it in the aux tank but I'm not too sure since I'm new to the 2 tank system and all. If anyone has any ideas or advice I'm all ears. Thank you in advance for any help!

Some of the older vehicles had a switching valve on the floor by the driver's seat.
The dash switch only controlled the fuel gauge and the pump in each tank. If you switched the dash switch you also had to switch the switching valve on the floor. What does yours have?

So far I only saw a switch on the dash that said main and aux for "fuel." Like I said, I just got this truck and I've been a little frustrated with it so far.

in that old of a truck there wasn't a pump in either tank Hanky. that switch controls a valve under the cab. the main tank is the rear tank. now for your charging system I would suspect that your battery get replaced, once that's done get volt meter and place it on the posts of the battery and with it running see what the voltage is if it's higher than 15 volts then you need to replace the regulator which is mounted on the radiator support next to the radiator if your still not satisfied with it replace the alternator