Fule Pump Issue

[huntingwiley]

I have an 03 21i with a merc 350 mpi. Today I noticed the batteries were completely dead. I changed the primary bat out with a new one and noticed that the high pressure pump runs continuously. The ignition is not on. The pump is only a year old. Could it be bad or is it more likely a relay some where?

Any suggestions are appreciated.

[IDBoating]

A motor going "bad" doesn't cause it to run continuously. A motor only runs when power is applied. So your idea of a relay is more likely, or whatever controls that motor's power.

And, since the motor is running continuously, it doesn't sound like it's bad at all. Obviously just because it turns doesn't mean it pressurizes the fuel properly, but if what you're trying to solve is the mystery of why your batteries are dead then I'd follow your train of thought on what CONTROLS the pump motor, not on the motor itself.

Report back on what you find. I am chasing down what appears to be a high pressure fuel pump problem myself at the moment (though thankfully, not on my own boat!) so this topic caught my attention.

[topaz surfer]

I think WA is on point. After reading his post I remember reading something about the two relays that are on the top of the motor on the drivers side and one being for the fuel pump. Try doing some research on that. Good luck.

[huntingwiley]

It was a relay that was bad that was causing the issue. Relay was located right by the ECM.