fuel gauge reading

[Beast496]

Hey all, tried searching for this one, but couldn't find exactly what it could be except for possibly a resistor issue. 85' K3500 with both left and right saddle fuel tanks were initially working as advertised. Gauge was reading accurate, switch was working, everything, etc. Then, one day, I went and filled both tanks, and when i got in the truck and started it up, the gauge only went to 1/4 tank, on both sides. Fuel level seems to correlate correctly from there, if you picture 1/4 tank as the new full lol. In other words, 1/4 =full tank, 1/8 = 1/2 tank, 1/16 =1/4 tank and so on. Again, this is for both sides. Was gonna start digging into it but wanted to see if anyone has had this problem before I do. Thanks.

 

[Jgonick]

I would start by checking terminals on back of gauge. Make sure the nuts tight. There is also the resistor on the back of the gauge that might be going bad (flat piece between two terminals) . Newer gauges have the resistor built in.


this video shows where the resistor is located at about 2:40 min
diag non-functioning fuel gauge

 

[Beast496]

I would start by checking terminals on back of gauge. Make sure the nuts tight. There is also the resistor on the back of the gauge that might be going bad (flat piece between two terminals) . Newer gauges have the resistor built in.


this video shows where the resistor is located at about 2:40 min
diag non-functioning fuel gauge

Thank you. I’m 99% sure it’s a resistor and this video makes finding where it is a piece of cake. Much appreciated.

 

[Jgonick]

I'm guessing the gauge, but it wouldn't hurt to also check all the pink wire's connection points.

 

[Dukester68]

I would start by checking terminals on back of gauge. Make sure the nuts tight. There is also the resistor on the back of the gauge that might be going bad (flat piece between two terminals) . Newer gauges have the resistor built in.


this video shows where the resistor is located at about 2:40 min
diag non-functioning fuel gauge

Can you purchase a new resistor anywhere sir?? Thank you

 

[mcarlo86]

Hey all, tried searching for this one, but couldn't find exactly what it could be except for possibly a resistor issue. 85' K3500 with both left and right saddle fuel tanks were initially working as advertised. Gauge was reading accurate, switch was working, everything, etc. Then, one day, I went and filled both tanks, and when i got in the truck and started it up, the gauge only went to 1/4 tank, on both sides. Fuel level seems to correlate correctly from there, if you picture 1/4 tank as the new full lol. In other words, 1/4 =full tank, 1/8 = 1/2 tank, 1/16 =1/4 tank and so on. Again, this is for both sides. Was gonna start digging into it but wanted to see if anyone has had this problem before I do. Thanks.

My dad had an '83 K20 that was just like that. My brother @cmichels83 has that pickup now. I am pretty sure it is the resistor behind the fuel gauge.