GM Fuel Pump control scheme

[WEG1192 at aol.com]

To me its obvious that Steve Ravet was right in that the OP switch is used to 
keep the pump running during CPU failure, otherwise limp home wouldn't work 
period. I can also say for certain that the ECM keeps the pump running as 
long it recieves ignition pulses from the distributor. To say that the OP 
switch is a backup for the F/P relay doesn't hold much weight to me. Also, 
the OP switch isn't a safety to shut down the pump since if the engine stops 
with the key on, the ECM will shut the pump off due to the lack of ignition 
pulses. The only plausible resaon left is to keep the pump running during 
limp home mode. JW
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