When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
how i heard it, pump doesn't run in 'on' position, only during cranking. oil pressure sensor wire to that control module in pass foot well, senses oil pressure and in turn energizes the fuel pump.
Some 12A pumps run only when cranking as well, like yours as you discovered. I believe the change was made in 84, but don't quote me. It's 83 or 84.
I'm not familiar with the later series fuse box, but there should be a fuse for the pump or engine or something. In my SA I have one fuse that kills everything engine related (ignition, fuel, etc.). Try to actually disable the fuel pump, especially if your ignition system is disconnected but not disabled - wouldn't want to ignite that big container of fuel sitting on top of the engine.
Anyway, you want to be cranking with the plugs out until there isn't much of anything coming out of the spark plug holes. Since it's carbed it will still be drawing in some fuel from the bowls (ideally you should be flooring it while deflooding so that it can breath), but the spray due to the carb coming from the plug holes will be minimal. It's a good idea to put some rags opposite the holes as well to catch whatever fuel/oil flies out from the main flood, although it looks like may already be past that point.
Once the worst of it is out, put back in the spark plugs (clean them first) and reconnect/enable the ignition system. If you can crank it without fuel - but with spark - for a little bit that can sometimes help to clear out anything left over. After that plug in the fuel pump again and try to start it; in theory it should catch.