Electric fuel pump install

[ricarbo]

If it's of any interest, here's how I would wire the relay.

By reference to the relay terminals:
terminal 85 goes to the supply side of the ignition coil. possibly via a 'push to break' switch to enable the pump to run when there is no oil pressure. The switch allows you to fill the carbs before attempting a start. Of course, the mechanical pump doesn't allow this but starts to work regardless of oil pressure, which is presumably a bit quicker. I'd add the switch to save the ring gear from unneccessary wear, but it does mean two extra cables into the cabin and finding somewhere for a switch and bracket.

teminal 87a goes to the always live side of the starter solenoid.
terminal 30 goes to the new pump.
terminal 87 goes to the starter side of the starter solenoid.
terminal 86 goes to the oil pressure switch.

The relay base I specify has provision for 3 fuses.

The circuit only draws power from the ignition switch if there is no oil pressure, i.e. it does not load the ignition circuit in normal running and I think that is a good thing.

The cable colours are my view of what is correct and you may have a different view.

I don't know how the circuit would be different if you were to use an inertia switch, as I don't know if these are normally closed or normally open.

I added an oil switch to my twin cam, wired to an audible alarm, because I don't look at the oil pressure guage when steering round corners. I was surprised at how UK roundabouts result in NO oil pressure. and will incorporate some sort of sump baffling, soon!

Richard