Michael, according to Bentley, this is the sequence of operation:
"During engine cranking, the fuel pump is supplied power from Terminal 50 of the ignition switch (hot in start position) through the fuel pump relay. Incoming air then causes the air flow sensor plate to lift and
open the sensor plate contact.
This de-energizes the fuel pump relay coil and routes Terminal 15 power of the ignition switch (hot in run position) directly to the pump."
Hope this helps you.
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Doug
'81 SC Coupe (aka: "Blue Bomber")
Canada West Region PCA
members.home.net/zielke/911SC.htm