73 240 JTR Conversion fuel pump wiring and tach wiring

[Guest 350zgto]

This is posted as an aid to others. My 6/73 240 came with an electric fuel pump installed at the factory. The factory fuel pump relay shuts OFF the fuel pump when cranking, to rely only on the mechanical fuel pump during crank speeds less than 400 RPM. Above 400 RPM the relay switches the fuel pump on, so do not use the factory fuel pump relay in your V8 conversion as the pump will not be on during cranking. I mention this because there can be quite a variance in factory wiring in a 73 and the factory manuals are rare and expensive, so most of us do not have one. Also my car had a 3 wire tach with the early face with the 6500 RPM redline like an early 240. It also had an ignition transistor unit mounted behind the heater control panel, no mention of this part in the factory manual nor Haines. The tachometer wiring colors did not match the JTR manual for 240 nor 260, nor do they match the Nissan factory manual for the 73 240 which shows a 4 wire tach, nor do they match an early 260, per Haines Manual. I had to split the harness' open and manually trace all the wires to learn this, now hopefully you won't have to. B/W to coil + (watch out, there are 2 B/W wires), Black is sensing wire tach to - coil, and Black again is tachometer ground. This was factory wiring, uncut with the original factory part # stickers on them.