QuestionQUESTION: What is the correct wiring configuration for the sending unit of a positive ground, 1964 MGB Roadster and a SMITHS fuel gauge 2300/02? Is the gas tank or sending unit supposed to be grounded somewhere? If so, where and how? If the word "TOP" on the sending unit means "This side UP", then I get a "Full" reading on my gauge when the tank is empty as soon as power is on. If I flip the sending unit so "TOP" is upside down, then my gauge reads "Half-Full"...I'm an optimist. I've got one wire lead on the screw extending from the sending unit and the other lead secured to one of the sending unit cover screws. This is how it was hooked up when I got the car and the fuel gauge didn't read correct then either. Frustrated in VA - David
ANSWER: Hi David,
The early MGB only had two connections on the sending unit. One to an insulated spade connector (green w/black tracer)and the other was a ground. (black wire)
If you look at the wire arm of the sending unit you can see it can only go in one way. The wire arm is bent down towards the bottom of the tank and the soft ring on the plastic float was put there so the float can rest on the bottom of the tank when it is empty.
Howard
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QUESTION: Howard,
Thanks for the speedy reply. I have installed the new sending unit..."TOP" up and float arm bent downward. As soon as I place the green w/black tracer on the insulated spade connector the fuel gauge races to the "full" mark, and placing the black ground wire to the body of the vehicle (positive ground) does not move the needle to "empty".
AnswerThe black wire must not be connected to the "Body of the vehicle" It must be connected to the "Body of the sending unit" for the unit to operate.
Also, look at your temp gauge to see if it is working. If it is not working then the problem also can be the voltage stabilizer for the two gauges. (usually mounted on the back of the speedo or tach.)
The temp and fuel gauges are operated at 10v, not 12v.
