after starting the engine the gas guage reads 1/4 full all the time. when car turned off it turns off

i just filled it up with gas so iknow it has a full tank.
i changed the lense recentyl, dont know if this would affect.

But, where could the problem be? gauge? sender unit in the gas tank?

i dont know if it ever worked, the car went to the paint shop soon after we bought it.

 

If it's on E or below when off, then rises to 1/4 regardless of tank volume, then I would suspect your fuel sending unit in the tank has gone south. A quick way to check would be to pull the wire off the sending unit terminal and jump it to chassis ground. Then hit the accessory switch. If it climbs up past 1/4 headed for the top, then click it off and make plans for a tank dive.

 

+1, sending unit

 

let the tank run almost empty and see if the float is full of gas ...could be as simple as that

 

if the float in the sending unit has a leak ,,then that's it,,,but thats the most likely sending unit

 

cool.... THANKS!!!!

another question is it easy or difficult to replace a sending unit?

 

Not difficult but is messy and can be dangerous. You're opening the bottom of the gas tank.

-if your tank has a drain plug, you can drain it.
-if not, then you'll need to siphon as much as possible out of the tank. A cheap electric fuel pump and some hose will do a great job at this.
-then you must climb under, disconnect the fuel line and the sending unit plug
-and remove the locking ring which hols the sending unit in place. To do this, you must use a BRASS PUNCH along with a deadblow hammer. (Led, brass, plastic, or wood). Whatever it is, use tools that WILL NOT SPARK.
-after you have loosened the ring, it will spin off and the sending unit will come out in your hand.

-Installation is reverse, however pay particular attention to the orientation of the unit when installing so that the sending arm will travel straight up and down.
-Also, use some silicone grease or vaseline to lubricate the rubber seal you are installing.