Fuel pump electric power failure

[Chris Berg]

Yamaha 115 hp F115TLRY.... won't start... fuel pump isn't making any noise when key is in the on position, I've been told you should hear it humm.... checking the two wires going to the fuel pump when key is in on position... 0 volts.... how many volts should it be? and I've checked fuses... clip is in emergency shut off switch, what is likely problem? Starter motor turns over just fine.... low pressure pump must be pumping gas because the motor runs for a few seconds but won't stay started.... what is the voltage of an outboard motor... 12 volt, pump should be a 12 volt pump?

[boscoe99]

Yamaha 115 hp F115TLRY.... won't start... fuel pump isn't making any noise when key is in the on position, I've been told you should hear it humm.... checking the two wires going to the fuel pump when key is in on position... 0 volts.... how many volts should it be? and I've checked fuses... clip is in emergency shut off switch, what is likely problem? Starter motor turns over just fine.... low pressure pump must be pumping gas because the motor runs for a few seconds but won't stay started.... what is the voltage of an outboard motor... 12 volt, pump should be a 12 volt pump?

The pump should run (hum) for a few seconds only when the key is turned on. Might be better to try and feel it than listen to it.

When you checked for voltage to the pump did you check from the engine harness red/yellow wire terminal, for the fuel pump, to a ground on the engine block?

The motor does not run off of the mechanical low pressure pump. Only on the electrical high pressure pump. If the motor starts and runs I would think the high pressure pump is working, if but momentarily.

Voltage of a motor is battery voltage (~ 12.6 volts) when the motor is not running. When the motor is running the voltage is the output of the electrical generation system. Nominally 14.6 volts. The fuel pump is a nominal 12 volt pump.