[T3] using original FI fuel pump wiring for aftermarket pump

Jim Adney jadney at vwtype3.org
Wed Apr 3 22:15:08 PDT 2019

On 3 Apr 2019 at 16:32, David Yaghoubian wrote:

> Thanks all for the responses. I will definitely install an impact switch if
> I end up doing the wiring separately/myself (great tip, Jim!) but I still
> have a likely dumb question about the original wiring. If that wiring and
> relay (however it is relayed) was sufficient to power the FI pump, shouldn't
> it just be as simple as plugging those same wires onto the new pump and
> turning the key?  One of my memories of growing up in the square was the
> sound of the pump when Momz would turn the key to the first position. =)

 When you had FI, the brain controlled the relay and the relay 
controlled the pump. This was done so the FI brain wouldn't have to 
handle the full pump current, just the relay coil current.

You can use the relay if you like. That would have the advantage of 
reducing the load on the ignition switch.

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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