Bilge Pump Problem

Snider · Posted: Thu Feb 25, 2021 8:13 pm Post subject: Bilge Pump Problem

Hi everyone,
I hopped on the boat today to check everything out in preparation for going out tomorrow, I noticed the bilge pump was not working. I figured oh well, it’s over 20 years old probably needs replacing. Just to be sure, I checked the fuse and the wiring, everything looked good, so I took the old pump out and checked the voltage at the pump with the switch on and it was 13.6 V. So I went to West Marine and bought a new 1100 gallon per hour rule 4164LPH bilge pump. I got it wired in and hit the switch and nothing, I took the pump out and checked the wiring again, with the switch on 13.9 V at the pump. Just to be sure I took the pump over to the car battery and touched the wires to that, and it came home. So I cannot figure why the boat wiring will not run the pump? Any good ideas?

thataway · Posted: Thu Feb 25, 2021 9:11 pm Post subject:

Just a guess. I suspect that there is corrosion in the wiring. You are getting the 13.6 volts with zero load on the circuit. (The 13.6 reflects the battery charger). But when you start the pump--lets say 7 amps, the voltage drops because there is. resistance due to the corrosion, and the pump will. not turn. Start going thru the circuit. Look at both ground and positive. It may be a butt connector with corrosion. Check all of the connectors-give them a good yank--as well as inspection.

Snider · Posted: Thu Feb 25, 2021 9:45 pm Post subject:

Thank you, in talking it over with a few others they came to the same conclusion. I was thinking if it were voltage drop the pump would at least try to click over, but that’s my plan for in the morning. Shouldn’t be to bad, just trace the wires back the switch panel and common bus bars behind the dash. I really appreciate the help! Guess my old pump was fine, time to change it after 20 years anyway I guess. Just wish they hadn’t glassed the housing down, pulled the gel coat up a little getting it out, of course the new pump has been redesigned and wouldn’t just snap down in the old housing. 😁

Snider · Posted: Fri Feb 26, 2021 12:53 pm Post subject: Solved

OK, so I figured it out. (if you don't care about the details skip to the next paragraph) When I hooked another hot wire up to the bilge switch the pump came on, so I knew the problem was in the hot wire. I thought the bilge was powered from the hot bus bar behind the dash because the bilge switch requires the battery selector to be on. What I figured out is that the bilge hot runs all the way back to the battery selector and hooks up to the selector post instead of one of the battery terminals. Not sure why it's like this. I would understand if it were hooked to a battery terminal so you could leave the bilge on with the battery selector switch of.

I found an inline fuse that I wasn't aware of back where the wires runs from the lazarette into the side combing. A boat is the only thing I can think of where you spend 4 hrs and $150 trying to solve a problem thats a 5 cent fuse, lol. At least now I have a new bilge pump and have a much better understanding of the boats electronics.