Fuel Gauge Problem

Q: Fuel Gauge Problem

I am having a Fuel guage problem. It always reads empty.

A: You can test the guage by grounding the brown wire, it should go to empty. Do this by grounding the female portion of the connector located in your trunk.. (its the dark brown wire) You may also test the sending unit with a multimeter (Ohms) from the connector in the trunk… The connector, I believe, has a dark brown wire, and a tan wire. The tan being your license plate light, and the dark brown being the sending unit. Place the red on your multimeter to the brow wire (male connector) leading to your sending unit (not the female back to the guage) and the black wire of your multimeter to a good ground on the body. Bump the car a few times to see the Ohms go up and down. If the tank is full there should be around 90 Ohms. If it is empty it should only be around 1 if I remember (somebody correct me if I’m wrong)

The sending unit float over time turns to “rock” but I don’t think it will effect its function. What I had seen on my sending unit, was that the coils inside were broken causing the unit to fail most of the time. (Many years of service eats up these coils which look like a bic pen spring around a thin piece of cardboard)

The sending unit turns out to be an expensive item. I had spent 70 + on my replacement, though it was for a 350 without the vapor return. This was a good deal, but the alternative would be to have Year One rebuild the faulty unit for over $100. The ohms should range around 90-100 when the tank is full. So with your sending unit acting as a “Variable Resistor”, and the guage acts as an Ohms meter (the higher the Ohms the fuller the tank.)

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