Bilge Pump Wiring and Troubleshooting
I want to go over bilge pump wiring, this covers new installs along with replacement of bilge pumps. There are three main wires on automatic bilge pumps and two wires on a manual pump. The automatic pump has the float switch built into the pump. I recommend these pumps over manual pumps anytime. You never know when you might be in a situation that you have a water leak and will not know about it until there is too much water in the boat.
Wiring an Automatic Bilge Pump
When wiring an automatic bilge pump in you will have three wires black, brown, and a brown with a white tracer on it. The black wire will go to ground or negative and the brown will be the switched wire. The switch wire is what runs to your switch and provides power to the bilge pump when the switch is turned on or to manual depending on the type of switch you have. The brown with a white tracer on it will be the automatic side that should have constant power to the pump even when the battery switch is in the off position. The float switch that is internal in the bilge pump is what opens and closes the power circuit to turn the bilge pump off and on. That is a safety that should be installed from the factory on your boat that enable the bilge pump to operate even when the battery switch is off.
Wiring a Manual Bilge Pump with Float Switch
If you are replacing or installing a new manual bilge pump, I advise installing a float switch. The float switch serves the same purpose of the automatic bilge pump internal switch. It should be wired straight to the battery positive and not go through the battery cut if switch if applicable. On a manual bilge pump, you will have two wires, a black and a brown. The black will be the negative and the brown will be the positive. When wiring a float switch into the circuit you will wire one of the switches to the brown on the bilge pump and the other wire coming off the float switch to the positive coming from the battery. If you want to wire it to a manual switch also, where the brown and the single switch wire come together is where you want to add a switch wire and run it to a switch.
Troubleshooting a Faulty Bilge Pump
If your bilge pump is not working at all the first place to start is make sure that the fuses aren’t blown and that power and a good ground are reaching the pump. I recommend that every boat owner carries at least a multimeter on their boat. A lot of issues with boats can be solved with a simple multimeter to verify that you have power and a solid ground. We can check both the float switch and the bilge pump also with a multimeter. For instance, on a float switch you can set the meter to ohms, and put each lead on each wire of that two wire switch. In this case the switch should be open not allowing power to flow through the switch to the pump to activate the pump. Once the switch is flipped up it closes and allows power to flow through.
If the float switch checks good, we can move on to the pump. Take the meter and place it in the ohms setting, put one lead on the brown wire and one lead on the black wire. The ohms measurement should be less than an ohm if the internal motor in the pump is not damaged. Any reading over an ohm the internal motor has locked up. Therefore the whole pump will need to be replaced.
