At 06:45 PM 10/11/98 -0400, Steven R Schultz wrote:
>.... If I understand this correctly the 0-70 reading registers when I
connect one wire on the multi-meter to the chassis and the other to the
sending unit with the gas gauge wire connected and the ignition off?
Yep. Should be somewhere between 0 ohms (empty) and 70 ohms (full)
depending on fuel level. 3 gallons should be around 20 ohms.
>I reversed the wires on the back of the gauge but it only seems to work
>one way.
Well then, probably right to begin with. Hope you puth the wires back the
first way around.
>I tried connecting a grounding wire from the chassis to the gas tank edge.
I will try it again with a heavier wire and a better connection to the tank.
One of the little screws holding the sending unit is a good connection
point. And there's a harness grounding screw right there on the frame,
just about 6" away.
>I think the next step is to drain the tank and pull the sending unit.
I had a gallon or two in the tank and didn't bother to drain it. With only
3 gallons in the tank, just jack up the right side of the car before you
remove the sender unit, and the fuel should stay mostly on the other side
of the tank, no spill.
>To check the 0-70 resistance reading with the sending unit out do I ground
the outer edge of the unit to the chassis with an alligator clip. leave the
gauge wire connected (probably not necessary) and connect the multi--meter
between the electric stud on the unit and the other wire to the chassis?
Or do I just pull the unit out of the car, connect one wire of the meter to
the electric stud and touch the housing with the other end and move the
float to vary the resistance?
If the sender unit is out, don't connect it to anything, test it by itself.
Put one lead of the ohm meter on the connection tab and the other lead on
the housing of the sender unit. When you move the float arm through full
motion range the resistance should go from 70 ohms (full up) to 0 ohms
(full down). And while you're at it, check that the float actually floats.
I had my sender unit out fiddling with it before I figured out it was just
a bad tank ground. I had forgotten to read my own note "Check fuel tank
ground", written about two weeks earlier. Duh.
Barney Gaylord
1958 MGA with an attitude (and sometimes a little humility)
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