Gas gauge issues 1939 P-8

[Guest Shoe1932]

Hello All,

I have always known that the gas gauge on our '39 has been a bit screwy. Anything below 1/2 tank could mean empty. The solution was to keep it above 1/2 tank. Well, as embarrassing as it is, I ran out of gas. With 3/4 of a tank no less. I got 2 gallons of gas in the car and she now reads full tank. I pulled out the shop manual and browsed over the fuel gauge section. There is a bunch of stuff about what he gauge will read if the gauge is wired incorrectly (ie. wires crossed or nor grounded....).

I want to do 2 things. Get the gas gauge fixed or working so that I know when to expect to run out of gas. I have a strange feeling that this is more than a wiring issue. Also, I would like to drain the tank. The drain plug is super tight and I do not want to break it off. Don't want to heat it up with torch briefly either or I will be posting threads about being the owner of a burned up P-8. The manual also discusses draining the tank from time to time. Is this as simple as some liquid wrench or is there a better solution to getting the plug out.

Thanks in advance for your help

[broker-len]

sounds like sending unit problems,,,,,,,,,,,,,,,,,,,the tank unit is nothing more than a variable resister,,,,,and just like old radios they get old,,,,,,,if you can get some of the spray cleaner and try to get it up the shaft and work it then get an olm meter and put across the circut and far as the draining,,,,,there is no easy way,,,,,try liquid wrench,,,but doint heat it

[Guest djc]

We just recently were faced with the same issues. Using liberal amounts of AeroKroil penetrating oil on the gas tank strap mounting bolts over a period of a week allowed us to easily remove the tank for a complete inspection and prep for sealing. We emptied the gas tank very easily by using a peristaltic pump and a 3/8" hose inserted throught the filler neck. Jacking up the right side allowed the gas to be sucked from the left side of the tank just below the fill neck, making the light tank easy to remove. The sending unit is removed by lifting it straight out of the top of the tank after removing the mounting screws around the perimeter of its mounting flange. I think there are 5 or 6 straight slot screws to remove. Again, a lot of soaking with the penetrating oil over a couple of days, and all the screws came out cleanly. Check the sending unit by applying 6 volts to it and then moving the float arm up and down. As it moves, you should see the voltage change on the other terminal in proportion with the movement.