74 CJ5 Fuel Tank Size

Looking for a little help. Have a 1974 CJ5 258, T-18. The Jeep seems to be all original except for some minor modification I have done. I seem to have a bit of trouble with the fuel system. Currently my fuel gauge does not work, neither does the speedo. A few times I have run out of gas while driving. When I fill the tank it seems to over spill at about 10.5 gal. If I wait I can cram another gal or so into the tank. Before when I would fill up I noticed that I could put as much as 12 to 13 gal in the tank. Now it seems that I only have room for about 10 or so gal. Do you think I need to replace my fuel sending unit? Would the filter sock on the end of the sending unit have any contributions of not be able to use all fuel in the tank? What is the fuel capacity assuming I have a stock fuel tank? When all the fuel system components are working properly how many gal of fuel does it take to fill the tank when the Jeep has run dry? Thanks for your help.

 

I thought the stock tank was 15 gallons but I could be wrong. None of my gauges work right now so I might not be the best source of info for the amount it can hold while full lol

 

I fight with my fuel tank and sender and gauge since a long time.
It is normally a 15 gal, some are 20. The sender is very week and can be badly positioned. I was short of fuel twice. Also the sender can be not touching the bottom, it is not only a sender but also the fuel entrance and if it is bent it cannot go deep enough.

The other problem is the electric part, gauge and sender.

It is easy to take off the fuel tank. Only difficult is to put all pipes in good position and screw well.

What I want to do one day with good weather :

put the tank down.
Open the sender part and check the sizes.
Take off the gauge.
Then make tests with the fuel tank not in position.
If necessary buy a new gauge and sender unit.

Its one day test but the only way to know.

The gauge and sender must be link well to the ground of the Jeep.
It is useful to draw wire lines for test. But afterwards, nothing can be wrong. IMO...

 

Hum, i did exactly as you did, my gauge when full indicate little more than half. I make test with the sender out of the tank and the problem semmed to come from sender. (when sender was i up position gauge show exactly the same as in the tank. So i was having another sender (brand new), so i give it a try and gauge was correct when sender was out of the tank (show full on gage when sender is up). But puting it in the gaz tank the problem came back and i have to run it like that.

ALso i notice that the filler tube plug on the side of the tank, so when fueling it seem to hard to fill the part un the gaz tank that is higher than the filing tube...