1984 Silverado Fuel Gauge Issue

[bd]

Ran some controlled tests using a contact K-thermocouple with simulated charging voltage regulated at 13.8 volts and ambient temperature stabilized at 77° F. 

After adjusting the fuel level sender resistance to 88 ohms, so the fuel level gauge indicated FULL, the net current flow through the gauge circuit measured 0.143 amp while the temperature of the ceramic resistor on the back of the fuel gauge stabilized at 93.2° F (barely warm). 

Readjusting the fuel sender resistance to 1 ohm, so the fuel gauge indicated EMPTY, the net current flow through the gauge circuit increased to 0.291 amp while the temperature of the resistor increased and then stabilized at 123.8° F (quite warm to the touch and similar to what you measured independently).

So, now we have some quantitative data.  The fuel gauge and resistor DO GET WARM!  It's normal!  So, there's no cause for concern.   

[The1984Silver]

Well thank you for that i was still wondering and worrying a little but its makes sense that they get hot.

Note: Alot! of info online is conflicting as far as what resistor to use for the gas gauge resistor test. I'm not a genius but from my experience!! I do not recommend using a simple radio shack resistor, is not a safe way to go about testing the gauge. Radio shack "my radio shack"doesn't make a resistor like the original that can truly deal with the low resistance which can mean high current, and that means heat! So what i mean is using a radio shack resistor could result in smoke and fire folks so be warned. Also if you think your sending unit is bad try to get a true ceramic GM fuel gauge resistor if possible before you pull it. Reason being my sending unit was functional but 2 gauges well make that 3 were crap and didn't work which leads me to believe with this many years on these trucks those ceramic resistors on the fuel
gauge are on their last leg or close to it.

Another thing: Not all bad fuel gauges will stay at 1/4 like stated in many repair manuals. Sometimes they can go way past full, to 3/4 and yes most of the will stick around 1/4. I know this because Ive tested 2 bad fuel gauges from the salvage yard plus my 3 and all were a little different even know they didn't work. As soon as the ceramic resistors in them however my 3 gauges work like a charm.