Gas Gauge - '79 Bus

[DjEep]

Gas gauge goes to 1/2 mark when full, then drops to "E" within 2 gallons. Does this sound like a sender or a gauge issue, or do I hafta get off my lazy duff, bust out the Bentley and a VOM, and start testing to find out?

[Amskeptic]

Gas gauge goes to 1/2 mark when full, then drops to "E" within 2 gallons. Does this sound like a sender or a gauge issue, or do I hafta get off my lazy duff, bust out the Bentley and a VOM, and start testing to find out?

Try a couple of lazy checks as far as poor connections at the fuel sender wire along the right frame rail, there is a ground screw for the ground wire accessible after the firewall is off but before you have to pull the tank. Connections at the gauge and vibrator can be cleaned. How did this symptom arrive, suddenly or over time?
Colin

[chitwnvw]

Gas gauge goes to 1/2 mark when full, then drops to "E" within 2 gallons. Does this sound like a sender or a gauge issue, or do I hafta get off my lazy duff, bust out the Bentley and a VOM, and start testing to find out?

Try a couple of lazy checks as far as poor connections at the fuel sender wire along the right frame rail, there is a ground screw for the ground wire accessible after the firewall is off but before you have to pull the tank. Connections at the gauge and vibrator can be cleaned. How did this symptom arrive, suddenly or over time?
Colin

Mine does the same (White '75). Must check out. Suspect sender and engine pull, which with 100k Gex is probably not far in the future. Fingers crossed.

[dingo]

Take the wire going to fuel sender unit, ground it and watch what your needle does. If i remember correctly there is a connector tee somewhere in the right rear wheel well. It's been awhile.

[chitwnvw]

Take the wire going to fuel sender unit, ground it and watch what your needle does. If i remember correctly there is a connector tee somewhere in the right rear wheel well. It's been awhile.

Seems like if ground was an issue that the sender wouldn't work properly for the first 1/4 to 1/2 of the tank. Am I missing something?

[dingo]

The fuel sender is a variable resistor (either wiper or other mechanism). By grounding the sender wire (not the ground wire), you are introducing zero resistance to the gauge. The gauge should hit empty or full, I forget which. This verifies a functioning gauge.

[DjEep]

I would assume zero resistance would be "full", since at "off" (infinite resistance) it is on the E.

I'll try cleaning the connections at the sender.

I actually never thought it worked at all, then when I topped it off for the rescue run from Waldport, it magically "worked".

[chitwnvw]

Makes sense. Thanks.