Bosch Motronic - Component Datasheet
Fuel Pump (G6) and Fuel Pump Relay (J17)
The fuel pump is of the high performance roller vane type that is located inside the fuel tank. Its operation is controlled by the fuel pump relay (J17) which resides in position 10 of the main fusebox in the 3B Coupe. Furthermore, the 12V feed to the fuel pump is protected by a 10A fuse at position S13 in the same fusebox.
J17 actually switches 12V power for many devices in the engine by means of its dual output pins 87 and 87a. These other devices are N71, N75, N80, Z19 and all of the fuel injectors. Checkout the schematics for more information.
The decision to trigger J17 into the ON position is made by the ECU when engine speed exceeds about 25rpm. This is done for safety reasons so that the fuel pump is shut off in any accident that is heavy enough to stop the engine.
trigger signal from the ECU to J17 is nothing more elaborate than a pin (#3) on
the ECU (same pin on 3B and ABY) which is switched to ground in order to activate the fuel pump
Last Updated 9th November 2007