I seem to have a battery drain that will kill the battery voltage in a week or less.  This is what I have found so far:

You did a good job narrowing down the problem..the one wire with the 20 amp fuse in it where when removed went to .13 volts is the circuit you want to play with the most...9 to .6 is the other drop to play with also..the wire that has 2 volts on it sounds like you are doing a voltage drop..which if it is 2 volts and not 2 milivolts you got a problem there..bad ground there..or the wire is shot..I am assuming you found the 2 volts by using a DVOM with a wire hooked to ground and the other touching the wire..ok..    Sounds like an alarm or something like that is staying on or activated..or even a fuel pump prime..not sure what that circuit goes to as it may have other stuff hooked to it besides the pump and oil gauge..are the door switches removed? This is going to be a fun one..

Rich

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My first parade at Carlisle 2010

I believe the in-line fuse is also powering your ECM in addition to the FP relay.

The courtesy light timer module is prone to failure, and can cause a small draw like this. Getting voltage on the "other" side of the orange wire with the fuse out could mean there is a slight back-feed of voltage from somewhere. Make sure the headlight switch is turned so that the courtesy lights are not "On" all the time while you're doing these tests....assuming the headlight switch is still connected.

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Joel Adams
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From what I saw on the wiring diagrams, the orange wire runs from the junction box at the battery to the FP relay, oil pressure sender and connector C451 on the ECM.  I disconnected the FP relay and OP sender but did not disconnect the ECM.  The voltage at the fuse is measured using a DVM with one lead attached to the negative terminal on the battery and the other attached to the outbound lead of the fuse holder.  I get about 2 volts on this wire with everything disconnected (except the ECM connector) and the fuse pulled.  I can pull the wire going to the ECM and it should go to zero, right?  Should I be seeing this voltage?

Messed around a little more today.  If I disconnect the ECM and ESC connections, I of course loose the voltage but as well loose the amp draw.  Plugging them back in, with the OP and FP relay plug last, my problem comes back.  Amp draw goes to about 0.14 amps.  This seems about right doesn't it?  I still have all the fuses pulled.

If I remember correctly, the ECM is pulling current all the time!!  Remember that it monitores 13 different functions.  I am niot sure how to check the ECM but I have a friend who designed that peice and I will ask him!!!  I, of course, have the ECM and PROM on my 81 !!

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http://www.corvetteactioncenter.com/kb/questions/118/1982+-+1991%3A+Service+Bulletin%3A+Parasitic+Drain+on+Battery+Ammeter+Connecting+Procedure this isba service bulletin for battery drain by ECM 91-14-8a

The saga continues.  Figured out today that I have power on a wire that should not.  The orange wire that goes from the hood louvre WOT solenoid relay to th ECM has 12+v even when it is not connected to the relay or ECM.  Pulled all the connections off the ECM and found power on the orange wire connector c452.  This should not have any power at all.  Power is feeding back through the ECM to give me the 2 volts on the back side of my fuse.  Disconnected C455 which is under the e-brake pad and lose the power at the ECM but still have it on orange wire at the relay and outbound side of the connector.  This wire goes into the main bundle that connects to the back side of the fuse box.