What is the purpose of a fuel relay on a Honda motorcycle. Why did they not hard wire the fuel pump to?

Question

activate when you turn the ignition key? I have three wires that come in to the fuel relay one from the engine start/stop switch, one from the spark unit and then one that provides power to the fuel pump. How does it all work? Why the spark unit? Whats the purpose of the relay?

Answer 1

What is the purpose of ANY relay?

to separate the power circuit, from other power circuits

Answer 2

Fuel turns off when the engine does not start spark unit might ground that relay. Many engines give 10 to 3 seconds of fuel pressure and if the oil pressure does not come up the relay turns off. Continuing to crank a engine that does not spark loads the crankcase with fuel and explosion can happen.

Answer 3

With the fuel pump hard wired to the ignition switch - if the bike were to get in an accident and crash, the fuel pump would remain on.

The fuel pump relay is powered by the ignition circuit from the ECM (electronic control modual - computer).

If the bike were to crash, the bank angle sensor turns off the ignition system and the ECM stops sending power to the fuel pump relay.

When the kill switch is turned to "off" - the ignition system is turned off and the ECM stops sending power to the relay.

Answer 4

For the same reason there is a relay on anything.  To control a high amperage circuit with a low amperage switch.