http://www.classiczcars.com/forums/showthread.php?s=&threadid=5997

I'm getting ready to swap an '80 60 amp alternator into my '73 240 and am using Bambikiller's excellent writeup as a guide. But I have a question that I don't see answered in it. I've attached a picture of the new alternator. You'll see a yellow arrow pointing to a connection that isn't in the write up. Anyone know what it's for?

The reason I ask is that I took the alternator to a parts store and had them test it. Their configuration didn't show connecting that pin and they were unable to get any output from the alternator. So I went to another store and their configuration did use the connector, and the alternator tested good.

I can't tell you what it does [at least on a 240 conversion], but you don't use it.

Someone once remarked that it was used on EFI but as I have all carbie cars I can't verify it. It puts out 8volts from memory?

Anyone else cast some light on it's use?

Just put the new alternator in tonight. My old regulator (that was only a few months old) had the battery voltage at 13.8 V when all was warmed up. The new alternator is at 14.6V. Pretty sweet to get almost a full extra volt! Dash lights are noticeably brighter :classic: And at idle, I can turn on the headlights, fog lights, and fan on high, and the ammeter stays right at 0, just as it should. I highly recommend this to all of you with older Zs.

One "unintended consequence" is that now when I turn on the ignition, the electric fuel pump turns on. This is even before I start the engine. Used to be that until the oil pressure built up (greater than 5 psi?) the pump stayed off. I understand this is a safety feature so that if there was a crash, the fuel pump would shut off when the engine died.

Thre is a part of me that likes this new "feature" as I had a problem getting started a few times when there wasn't enough fuel in floats. I guess my oil pump doesn't generate enough pressure when cranking the engine to turn the fuel pump on.

Of course, there is a safety issue now. Can anyone with a 73 running with an electric fuel pump tell me if their pump comes on with the ignition? And suggestions on what's going on here?

I was going to work on the AC box under the passenger side when I noticed that one of the relays mounted up there was very warm. Given I hadn't driven the car for a few hours that wasn't a good sign. Turns out it's the relay that controls the fuel pump. With the new wiring for the new alternator, I guess it's always "on" (which explains why my fuel pump comes on when the ignition only is on).

Unfortunately the wiring diagram in my factory manual only shows the fuel pump and does not include any of the circuit that shuts the pump off when the engine quits running. (BTW, I surmize that it quits when the alternator stops producing electricity, not when the oil pressure drops as I said earlier).

I'm guessing that given the electric fuel pump was added by the dealer on the 73s when owners complained about vapor locking, it was probably a field-fix that wasn't documented properly in the factory manual.

So my question is if anyone has the wiring diagram for the fuel pump circuit? Or perhaps the circuits inside the voltage regulator and the alternator (old one). If I had that I think I could figure out how to wire it up.