Motronic question (NAC)

[Joe Elliott <jee@domain.elided>]

I found myself working on a non-starting BMW this evening (another one)--my 
friend's 1983 Euro-spec 735i, which just decided not to start.  Why it 
won't start has me completely stumped, but I really haven't ruled 
everything out yet, so I can't complain.  My question is this--how is the 
fuel pump powered when the engine is running?  Unlike my L-Jet car, the 
Motronic airflow meter only has 4 pins, and seemingly no switch to turn on 
the fuel pump.  Does the ECU at some point decide that the engine is 
running and that the fuel pump should be switched on?

Joe Elliott
(In case anyone is wondering, the car in question will crank, and has 
spark, but doesn't fire at all.  The fuel pump is working, but beyond that 
we haven't tested much.  A book I have indicates that there should be a 
large resistance between two of the AFM pins for the air temp sensor, but 
the only two AFM pins that had any sort of continuity were obviously the 
flap-position pins.)
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