Triumph Repair: fuel tank sending unit, fuel tank sending unit, spade connectors

Question
QUESTION: I just replaced the fuel tank sending unit on my 1973
Spitfire. I cant figure out which wire connector goes where on the sending unit. There seems to be a T and a W near the  connections on the sending unit. I have a black wire (which must be ground wire) and a Green wire.  o the T and W mean something as to which connection goes where?? Thanks for your help have a nice day. JIm
ANSWER: Hi Jim,
The two connectors on the sending unit should be flat spade connectors and one should be directly attached to the metal part of the sending unit and the other spade should be mounted in plastic. The green wire with a stripe goes to the spade mounted in plastic and the black wire goes to the spade that is mounted directly to the metal part of the sending unit.
Let me know how you make out.
Howard

---------- FOLLOW-UP ----------

QUESTION: Follow up question: My old sending unit is exactly as you said . One connection connected right to the metal part of unit. other connection in plastic. But guess what. On the new one they are exactly alike neither fixed right to the metal part of sending unit. Both are sitting on a plastic washer. They look exactly alike. Is it possible to send you  a picture I have a digital camera? Ever hear of Indro-Stop? Thats name on box of new sending unit.. I thought about calling them but couldn't find them on-line. Does the letter T and W mean anything near connections-sure don't match any color code in manual.  Hope you can help. Thanks again for your time. Jim

Answer
Never heard of a "T" nor a "W" connection for any British car. It does not matter as there is a way to test it. You need either an Ohm meter or a 12v test light. With an Ohm meter you check for a direct connection from each connector to the metal case of the sending unit. That pin will be the black ground wire. The other pin will show a resistance between the pin and the frame of the sending unit. If you use a test light, connect the alligator clip of the test light to a 12v power supply. (You can do this at the battery) connect the case of the sending unit to the negative post of the battery. Touch each pin on the sending unit with the point of the test light. Both will probably light the test light but one will light it bright and the other will light the light dimly. The pin that lights it brightly is the ground (black wire). The other pin that lit it more dimly will change how bright it is if you move the float arm up and down. There is one other option. If neither pin shows any connection to the frame of the sending unit then test it this way but not until you confirm that neither pin has any connection to the frame. Connect both wires to the two pins and turn the key on and watch the gauge while you move the arm up and down. If the gauge works backwards, reverse the connections. Don't do this test until you have done the other tests first. The reason is you could do damage to your system if you didn't do the other tests first. This test is not a short cut, it is a test if the manufacture wired it this way. The letters "T" & "W" probably tell you which wire is which in what ever country that aftermarket part was made in.
Let me know.
Howard