Fuel Guage Woes

[MoHealey]

Unable to diagnose a faulty fuel guage on my 69GT. New tank and sending unit during resto, new voltage stabilizer.
Guage worked great for about 50 miles, but now the needle will only move to about 1/4 full at best (and, yes, it's full of fuel). All other electrics are working great. Have checked connections and continuity - looks OK.
Any ways to further isolate this to the sender or the guage itself?
Any help appreciated..
Thanks

 

[LarryK]

Checked voltage? Check ground for cleanliness ( paint or tape). Use a multimeter on ohms, remove sender and check for continuity in movement of sender. Might be stuck, might have to rotate mounting position to clear in tank.

 

[fogliner]

Could just be the float on the fuel gauge arm inside the tank no longer floating. Not a huge deal to remove the sending unit,just jack the car up on the right side to make the fuel flow to the opposite side of the tank(1/4 tank or less left in tank of course :b) and you can remove the sender quite easily(almost scary),Small hammer and a common screwdriver and tap the ring counterclockwise till the slots line up with the tabs.You should probably have a new ring and gasket onhand for re assembly just in case you bend the ring.Then just paint over it with black rust paint after you hook up the wire and your done.

The early MGB 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.

Hope this helps a bit...Mark