lund bilge pump problem

I have a 2003 lund 1700 pro sport. Bilge pump not working. It has a manual on and off switch at the consul. I pulled the pump disconnected it and checked the wires and had 12 volts to the pump. I had a spare pump which I tested on an external battery before connecting it to the pump. Pump would not run, checked power to the pump and no voltage with it connected. Disconnected the pump from the wiring and had 12 volts. Tested the original pump on an external battery and it works.

Anyone have any ideas?

Jon, do you have any aptitude to do a little testing?
If so, grab a 3157 light bulb, bend its wires out so you can make a test light out of it that will put a 45 watt load on the circuit when you connect it at the bilge pump wire connector.
Using your voltmeter or test light, start back probing the circuit through its power source, for some reason I am seeing a lot of corroded fuses at the fuse block regardless of brand of vessel.
Check the switch on both sides of the circuit as well, and check all grounds.
Hope that helps!!
The reason I suggest a 3157 bulb is so that you have a constant load indicator as you go, you never know when you will move a wire and cause a change in voltages/grounds.

Oh what do you know

I’ve had two constant loads, cost me dearly

If you look closely at the credits on the Apollo 13 movie with Tom Hanks you will see “lowboy” clearly listed as the consultant for all things mechanical and electrical. It’s why the were able to get back to Earth!
Depth of knowledge or what!?!?!

Thanks for the advice. The console has a bank of glass cartridge fuses, I checked all of them before I pulled the pump. The fuse holders are not marked so it is difficult to know which one was connected to the bilge. I found 2 bad fuses and replaced them before I Pulled the pump. I will dig deeper.

Thanks

Ya you have a bad connection somewhere in the line, when a load is applied you loose power. Start from the Bilge switch and go from there. The switch can be the culprit also so do not over look that.