> On Mar 21, 9:13 am, aarcuda69062 wrote:
> > In article ,
> > "Scott Kelley" wrote:
> >
> > > I am putting an electric fuel pump into an older car & want to use a fuel
> > > pump relay that will sense when the engine quits and shut off the pump.
> > > I
> > > know that many vehicles had this type of relay.
> >
> > > I'll probably get something out of a wrecking yard - I would prefer to
> > > get a
> > > relay AND socket. Any suggestions as to what vehicles to steal this
> > > from?
> > > Reliability & availability are the two obvious issues that come to mind.
> >
> > Late 80s early 90s GM or Ford truck
> >
> > > Again, I'm not looking for a normal relay, but a "fuel pump relay" that
> > > remains active only as long as it is receiving pulses from the ignition
> > > tachometer line.
> >
> > Are you building a relay control circuit that responds to the
> > tach pulses or do you think that a relay can literally be run
> > from the coil negative?
> > The latter isn't going to work.
> > Running thru an oil pressure switch would work much better.
>
> I don't like the oil pressure switch idea simply because there may be
> situations where you make the educated decision to fry your engine to
> get out of harm's way. but that's just me.

Not sure I understand...
> The VW relay works like this; when power is applied to it (i.e. you
> turn the key on) it will run for 5 seconds and then shut itself off -
> this pressurizes the fuel rail for initial startup. Then when it
> starts receiving pulses from the coil, it will latch in until it no
> longer receives a signal from the coil.

Didn't know that was how VW did their fuel pump relays. Gotta store that one in the data banks. Thanks.