Alarm as soon as power is turned on - Nissan 90HP

A strange one for you guru's.

Have a 1999 90hp Nissan outboard. The original problem was that it would only rev to about 4000 RPM's under load. It would rev to the normal 5500 RPM's in neutral. Also noticed that the voltage meter was only reading about 10 volts wide open.

Decided I needed to change the batteries before taking it out of the water to have someone look at it. (Had spare batteries on hand and have been burned by this before).

Hooked up the new batteries to my Perko medium duty battery selector switch.

Now as soon as I turn on the selector switch to any setting, I get an alarm. The alarm is constant. If I start the motor, the alarm goes away. I did notice that while the motor is running, the voltage meter stays at zero.

I have no clue what is causing the alarm and would greatly appreciate any assistance you experts could give this rookie!

Thanks

What is your model? Probably NS90A, not a TLDI (NSD90A)? I assume you have remote control, and that's where the alarm beep is coming from? Your boat and/or motor has a (possibly very serious) wiring fault. Possibly a reversed wire for ground somewhere. Since your voltmeter could be wired in any of a number of configurations, I'm not 100% sure what all this ads up to, but here are a couple of observations:

1. Something changed when you swapped batteries. You didn't have the alarm before that.
2. 10v would likely be insufficient to even start the motor. So that reading was incorrect to start with.
3. 0v means that the voltmeter is not seeing any voltage at all. So that should be a clue to finding the wiring fault.

I would consult with a local reputable marine electrician before going any further into the WOT RPM performance issue.

Thanks for the reply Paul,

You were correct with the wiring problem. Didn't notice a wire installed by the previous owner that went directly to the positive side of the battery selector switch. This wire must have had a short in it and was feeding current into the ground circuit. Disconnected the wire and the alarm went away. Voltage meter is now working as well.

Before taking this NS90A to the shop about the RPM issue, I decided to change the spark plugs. Put it back in the water and now it runs great! Long story short is that I was running on two cylinders with my three cylinder motor. Given the fact that it ran so smoothly on two cylinders, I would have bet the farm that it was not a spark plug issue... Good thing I'm not a betting man!

Either the old batteries and the short in the wires was causing the low volatge condition as it is now running at about 14 volts.

Thanks for the advice and happy boating...!

Chet