These may help:

 

You may wish to buy a later 280z oil pressure sensor and connect a normally open switch.  The switch would wire to 36 and 39 and close when the engine was running (usually not in a crash).  You would have to keep the EFI relay to keep the functionality.

 

 

 

Haz, I said I removed all relays but now remember I did not remove the EFI relay. I did leave it installed. Removed everything else.

 

Blue's right, that's why I said check your fuel pump circuit. Not sure if its the same as the 77. 

 

It looks like the 75 use's a different EFI relay than the 77. At least it seems that way, there are two different part numbers. So my way of wiring probably wouldn't work for you anyway. Besides I still can't completely remember what I did. It was 1994, 21 years ago.

Sorry I couldn't be of much help.

This helps guys. Thanks.