GM Fuel Pump control scheme

[Shannen Durphey]

Uh-oh.  You've got an orange and you're trying to tell me my apple's not
the same color.

Wes Branchflower wrote:
> 
> I thought the ECM would run the fuel pump for approx 10 seconds, then stop.
> My brother used to have a VL commodore, when he turned the ignition to ON
> (not start) the pump would go on for about 10 seconds, then stop. (I know
> this cause his fuel pump was REAL noisy ;)
> 
> This leads me to think 
> that the fuel pump is activated by the ignition, for
> a brief 'turn on' time, after which, is turned off. When the engine starts
> (off the pressure already in the fuel rail), the engine's oil pressure
> switch would take over the control of the fuel pump. This makes it so if
> ever you loose oil pressure, your engine will shut off. (saving the motor)
> 
> Does it seem right?
Not in the GM-usa market.  Yes fuel pump relay operates for a short time
then turns off if the key is on and engine is off.  As soon as the ecm
starts recieving reference pulses from the ignition module, it closes the
relay to again operate the pump.  

At this point you should be considering getting some good service
information (like a service manual) or doing some testing on your
brother's car.
sd
> 
> remember this is a nissan S6 found in the VL's. not a GM.
> But i think it could be a very similar design.
> 
> If it doesn't already do this, i'm definetly making this modification on my
> engine.
What modification?  Removing the oil pressure switch?
Shannen
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