[s-cars] Bosch's words on Fuel Pump Voltage

[Dave Forgie]

Rolf:  The intent is to stay safe.  We (Sean Douglas and I) are going to
cut the fuel pump wires near the pump and use them to drive a new relay
that is connected to the battery.  The relay will be under the rear
seat, near the battery and there will be 14 or 16 gauge wire from the
battery to the relay and the relay to the fuel pump.  There will be new
15 amp fuse holder and fuse added to this circuit to protect the pump.
As far as the OEM electrics know, there will be no difference - if there
is a system to automatically shut down the fuel pump it would still work
- except it will first de-energize the relay which, in turn, will drop
the fuel pump out.

Sean has done a static test of this system with a direct connection from
the battery to the fuel pump and found the voltage was 12.2 V instead of
the 11.75 V before.  This lead to an 2 to 3 psi increase across the
simulated (with an air compressor) 0 to 28 psi "boost" pressure.  We
presume that with the relay system and the pump getting 13.2 V or more,
the low pressure problems, e.g. 80 psi instead of 86 psi at 28 psi
boost,  will go away - for good.  Sean is going to beat me to this
install so I hope to see his post soon.

Dave F.