GM Fuel Pump control scheme

[Bob Wooten]

I have beenthining about this for a couple of days  & i am still confused. 
if this were in fact to kill the engine if the oil pressure dropped below
the switch threshold & that the redundant CPU relay was just for starting,
then this would make a lot of sense (kind of).  I would think that putting
in a switch to tell the cpu OP OK or OP BAD would do the same thing.  the
thing that i don't get is that my car does not have a OP switch & it has
never had a problem with it running.  this tells me that the cpu must be
turning on the FPS relay & keeping it on (& it is obviously not hot wired
on as the CPU turns in on when i turn the key on & then turns it off until
the motor is running).  this tells me that the OP switch is a completely
redundant system.  the question is why.  

It does not make sense to me that the general would put this in because the
relays have a tendency to fail.  if that were the case then good
engineering says that you spec a higher amp relay or put two of them in
series with each other so that the cheaper less amperage relay can drive
the coil of the power relay (kind of like a darlington pair or a industrial
controller).  one of the gents on the list suggested that this had to do
with limp home mode & that does make some good sense.  If i am right the
resistors & "stuff" on the memcal does something to the cpu to control
injectors, the ign module does spark & the other thing has to be fuel.  I
would think that there is a more high tech approach, but sometime
simplicity is the best way to go.  

Am i thinkin' to hard?  
thanks for listening. 
BW




<Snip>



--- Bob Wooten
--- r71chevy at earthlink.net
--- www.r71camaro.homestead.com



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