GM Fuel Pump control scheme

[Shannen Durphey]

Wes Branchflower wrote:
> 

> >What modification?  Removing the oil pressure switch?
> >Shannen
> 
> No, making some sort of circuit to disable the ECM's relay control when the
> car is running. That way the only thing keeping the fuel pump going is the
> oil pressure switch (held closed by the running engines' oil pump)
> If the oil pump failed, there would be no more pressure to hold the oil
> switch closed, and the engine would stop. (saving it from running w/o oil)
> Thinking about this it'd probably be easier to just wire up the ignition to
> the oil switch somehow. A simple circuit to override the oil switch to get
> the ignition going while cranking, then off when the engine starts. This
> might work better so the engine doesn't run that extra litte while off
> pressure in the rail.
> 
> You might think 'why bother' but with a soon to be $3000 built race engine,
> which is known for oil pump problems, I will :)

Well, you'd better find something besides the GM oil switch.  That thing
closes with about 2 lbs of pressure.  Not much chance to save an engine
running at 3k rpm if the fuel shuts down at 2psi oil pressure.
Simple fix, don't install the relay.  Use a button as a primer to aid in
starting, and run off the oil pressure switch.  Disable any fuel pump
voltage codes.
And yes, ignition kill is much better as the ecm shuts down fuel when it
stops getting reference pulses.
Shannen
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