K10 fuel gauge problem

[ak70]

Hi, guys. I just got a k10 1.0 (1991 model). And recently I noticed that the fuel gauge was not working properly. According to the spec, the capacity of the fuel tank should be 40 liters, but when the fuel gauge indicates roughly 1/4 fuel in the tank, I can just fill it up with 13 ~ 15 liters. Does anyone have an idea about what went wrong?

 

[imp124]

there may be quite a bit of sludge in the tank? or possibly a sticking float in the tank, must admit ive never had the sender unit out so i dont know what it looks like

 

[ak70]

Not sure about sludge. but there should not be a sticking float. When the tank is full, the gauge indicates properly. However, it drops really fast.