[Gmecm] FW: Undignified death of a project :P (ECM control offuel pump)

[Steve Ravet]

That's what it does.  No ignition ref pulses, the computer shuts off the
fuel pump.

--steve 

> -----Original Message-----
> From: gmecm-bounces at diy-efi.org 
> [mailto:gmecm-bounces at diy-efi.org] On Behalf Of Rob Handley
> Sent: Thursday, September 13, 2007 3:46 AM
> To: gmecm at diy-efi.org
> Subject: Re: [Gmecm] FW: Undignified death of a project :P 
> (ECM control offuel pump)
> 
> I haven't looked at this area of code but, on the assumption 
> that software running in the ECM can turn the fuel pump on 
> and off via the relay, then presumably it would be possible 
> to add some code which turned off the fuel pump if the engine 
> stopped running - providing a useful safety feature(?)
> 
> Have I missed something?
> 
> Robin
> 
> ----- Original Message -----
> From: "Steve Ravet" <Steve.Ravet at arm.com>
> To: <gmecm at diy-efi.org>
> Sent: 10 September 2007 15:59
> Subject: [Gmecm] FW: Undignified death of a project :P
> 
> 
> A note from JW regarding the fuel pump relay and oil pressure switch.
> 
> --steve
> 
> The Oil Pressure Switch that runs the fuel pump isn't about backing up
> the Fuel Pump relay, which it does as a side benefit.  It is about the
> Backup Fuel function of the older (pre early '90s) ECMs.  If 
> the digital
> core fails in these boxes, the distributor or DIS is put in 
> BYPASS mode,
> allowing the engine to run on the base spark, the Fuel 
> Injectors are run
> by the Backup Fuel Device in the ECM (analog fuel injection, what the
> calibration resistors are for), and the Oil Pressure Switch runs the
> pump.  The BFD was removed later when it became untenable to have
> redundancy like this and confidence in the controllers increased.  It
> would be cheaper to use a more reliable relay then add in a parallel
> switch for the Fuel Pump.
> 
> JW
> 
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