Triumph Repair: battery drain, triumph tr 4, darkness of night

Question
QUESTION: On my Triumph tr-4 the battery drains in 4 days of just
sitting. The battery tests good, it is nearly new. Nothing
is left on. In the darkness of night I have lifted and
replaced the battery cables repeatidly to see if I can see
a tiny spark of drain. None is visible. However if I turn
on the ignition switch, I do see that little spark.
Any thoughts on this problem?

         Thanks much   Jerry

ANSWER: Hi Jerry,
A rough test of a battery drain in these older cars is to turn everything off and remove either battery cable and put a 12v test light between the cable and the post. If it lights the test light you have a drain and it is time to get out the wiring diagram and your test light and start eliminating circuits. I usually start by removing all of the fuses and put your test light across each set of contacts for each fuse and if you locate one that lights the test light, refer to the diagram to see what item/s that circuit has on it.
If it don't light the test light on the battery cable test, you need to have the battery tested and the charging system.

You said you see a little spark when you turn on the ignition. Where do you see a spark, You should see NONE anywhere. Or do you mean you see a spark with the ign on when you remove and replace the battery cable? That's normal.
To test the charging system,
Put a volt meter across the battery posts and set the RPM at a fast idle and read the volt meter. If it is not 13.8 to 14.5 volts, you have a charging problem. A hot (just run engine is easy to start on a run down battery and cold engine is not easy to start.)
Let me know,
Howard
Howard

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

QUESTION: Hi Howard
A test lamp placed between the battery post and battery
cable does show a drain. By the process of elimination
I am after the drain. It goes toward the temp gauge or
beyond that point. Fun, fun............

         Thanks for the tip

         Jerry
ANSWER: Let me know what you find.

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

QUESTION: Hi Howard
I did find the source of the battery drain.
The sending unit at the gas tank had a high
resistant ground,on the hot post.
Being a telephone man for many years made
tracing the problem much easier.

         Thanks again for the tip!


         Jerry

Answer
Hi Jerry,
The tank sending unit is suppose to have a high resistance ground, that's how it works. There should only be one colored wire going to the sending unit and it comes from the fuel gauge. Which is powered by a voltage stabilizer mounted usually on the back of the speedo and it only powers the gauge with 10 volts and only when the key is on. So it should not be a source of a ign. off drain. If it is powered when the key is off there is a wiring problem. The only exception to that is when a car is equipped with a low fuel warning light. But even then there are two colored wires going back to the sending unit but both are not hot when the key is off.
Most of the sending units I remember that had the low fuel warning light had three flat spade connectors on it. One was ground and easily noted as such. The other two were different sized flat spade connectors so the wrong wire was not connected to the wrong spade.
You need a wiring diagram for the car. to confirm the connections. If you don't have one let me know I will either give you color codes for the tank unit circuit or E-mail on to you if you want.
Let me know,
Howard