67 Fuel tank problems

[willowbilly3]

Keith is right about the short pickup tube. One out of a chassis mounted tank would fit but be too short. On the cab mounted tanks I have found that the float/sender just isn't welll matched to the tank size. I fiddled with one on my last 68 for a couple hours and couldn't get it accurate at both ends of the travel. If you bend the float to read full then it hits empty when you still have 1/4 tank and if you put it to read the last part of the tank accurately it will only go a little past 3/4 when full. Basically it is only capable of reading 3/4 of the tank no matter where it is set. A solution would be to extend the float arm. Throw a 5 gallon can of gas in the back and drive it until it is empty on each tank and you will see where your range is.
And the P.O. may have made the same mistake I did. I had bought a 75 bronco and walked a couple miles off the freeway when it ran out of gas because I thought the switch changed the tanks and all I was really going was switching the guage. Even after putting in 5 gallons it still wouldn't go (put it in the wrong tank) After crawling around underneath I see the hoses going to the valve.
You might want to drain the frame tank and put some fresh gas in before you use it but it is a mechanical valve so no reason it shouldn't work if it holds gas.
My crewcab has those aftermarket side tanks outside the frame. I only use the one on the drivers side and it holds 9 gallons. It has no guage so I use it first then fill up when the main tank hits empty as I have about 3 gallons left in there then.