"I think the eletric fuel pump power circut is wired so that oil pressure is required for the electric pump to run."
That's NOT true with those vehicles. The fuel pump relay (operated by the 'puter) and the fuel pump oil pressure switch are in PARALLEL.
The fuel pump will run as long as the 'puter keeps the relay energized 'cause it knows the engine is cranking or running OR as long as the oil pressure switch remains activated.
The oil pressure switch serves as a fail-safe for the relay, in the "ON" mode, meaning if the relay or relay circuit fails the fuel pump will still get energized, but after a longer cranking period 'til the oil pressure switch gets activated.
I know that flies in the face of conventional wisdom, but that IS how GM set these system up in that era. The oil pressure switch is redundant, and the vehicle will operate normally without it, AS LONG AS THE RELAY AND ASSOCIATED CIRCUITS ARE PROPERLY FUNCTIONING.
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Today's Featured Article - Usin Your Implements: Bucket Loader - by Curtis Von Fange. Introduction: Dad was raised during the depression years of the thirties. As a kid he worked part time on a farm in Kansas doing many of the manual chores. Some of the more successful farmers of that day had a new time saving device called a tractor. It increased the farm productivity and, in general, made life easier because more work could be done with this 'mechanical beast'. My dad dreamed that some day he would have his own tractor with every implement he could get. When he rea
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