Gas gauge shows only 1/4 full

[project_chevy]

hey everybody. I tried using the search function but didn't come up with anything to help me so I'm asking you all. I have an 86 Silverado K10 with dual tanks. I can fill both tanks with at least 10 gal of gas but no matter how much fuel I have the gauge never reads past 1/4 tank. Once I reach about 1/4 left it works fine down to empty. It does this with both tanks.

Is it a wiring issue? Any suggestions on where to start would be appreciated.

[DFAA]

If the gauge behaves the same regardless of which tank you have selected, I would have to say its the gauge going bad(or wiring at the gauge), and not the tank sending unit(s). Check the wiring at the back of the gauge, but it may have to be replaced.
BUT, I will defer to others with better suggestions.

[velojym]

Mine's about the opposite. It works fine from full until it reads about 1/4, then it stops.
My quick fix, for the now, is to top the tank when it gets to half.

...and pretty soon I need to get it fixed so that I can use both tanks.

[AceX]

My buddy had this same problem in his '74 Blazer. IIRC, we replaced the sending unit and it worked out.

[82BlazerMan]

My 82 blazer was showing a 1/4 of a tank when I filled it up and went down slowly through the 1/4 of a tank area.  I replaced the gauge and now all is well.  My vote is to 1st try and replace the gauge.  Tracing wiring sucks.  Got the gauge from a junk yard too.  Easy $10 fix.

[velojym]

I'm wondering whether the problem with my truck is that simple (the left tank was said to be inoperative).
I ran with it switched over, and it kept running. Of course, if the switch is bad, then I was probably just
still running off the "good" right tank.