Posted by Keith in Washington on Thursday, March 04, 2004 at 11:31AM :
Last night I tried to fix my gas gauge again. It is always pinned at Full. I have a 6 volt system with a single lead sender. Here is what I found.
I removed the sender and it appears to be working. I get readings of 16 to 100 ohms. 16 is at the full position if I remember correctly. I also cleaned the sliding contacts. I also cleaned off the sender and the hold down ring to make sure that there is contact.
I then reinstalled the sender and left the single wire disconnected. I then connected my volt meter between this wire and ground. I read 5 volts which seems OK. The fuel gauge was pinned at full.
Next I connected the volt meter between the wire and the terminial of the sender. It read 3.5 volts which makes sense since the tank is about 3/4th full. The fuel gauge was still pinned at full.
My guess is that the sender is just fine but the fuel gauge seems to be malfunctioning (possibly shorted out). Any suggestions as if I am correct or are there other tests I should do. I did not get around to removing the fuel gauge. How would one test the fuel gauge? All I can think of is applying different voltages across the pins and watching the meter respond. This could be done with 1.5 volt batteries which would give me 1.5, 3.0, 4.5 and 6 volt tests which should get me around 1/4, 1/2, 3/4 and full on the gauge.
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