fuel gauge reading

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Beast496

Junior Member
Joined
Feb 26, 2024
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Location
Fallon, Nevada
First Name
Ron
Truck Year
1985
Truck Model
Sierra K3500
Engine Size
496
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

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Jan 12, 2017
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Location
West Texas
First Name
Joel
Truck Year
1985
Truck Model
K10
Engine Size
350
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
 
Last edited:

Beast496

Junior Member
Joined
Feb 26, 2024
Posts
3
Reaction score
7
Location
Fallon, Nevada
First Name
Ron
Truck Year
1985
Truck Model
Sierra K3500
Engine Size
496
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

Full Access Member
Joined
Jan 12, 2017
Posts
335
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Location
West Texas
First Name
Joel
Truck Year
1985
Truck Model
K10
Engine Size
350
I'm guessing the gauge, but it wouldn't hurt to also check all the pink wire's connection points.
 

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Dukester68

Member
Joined
Sep 25, 2024
Posts
40
Reaction score
35
Location
Arizona
First Name
Gary
Truck Year
1986
Truck Model
c2500
Engine Size
350
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
 

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