Bilge pump blowing fuse on auto

[PhatMan]

HELP! Boat is a Ranger RP190 aluminum center console. The second year I owned the boat the Bilge pump would come on with Auto switch and not turn off, I assumed it was the pump and changed it. When I changed it the Auto would not work but the pump worked with the Helm switch, well 4 years later I decided to change the bilge because I leave it in a wet slip while we camp and the first couple of days we are expecting rain on our next trip. Now on to my issue, the pump still works with the Helm switch (new pump) but when I test the float switch (internal) it blows the fuse. This is a brand new pump, utilizing factory wiring. I assumed I had a bad pump so I bench tested it with a fuse inline, pump works in manual and auto with no issues. I chose to bench test my old pump as well, turns out the auto function works on that one as well and the pump it good. The hot wire for Auto is wired directly to my rear battery (just like factory) and the rest of the wiring harness runs to the center consol. I pulled the wiring diagram, the entire system shares a ground directly from the battery. I have tried everything I can think of, breaker fuse at helm is fine or the manual pump switch would not work. Why would it work in manual and not Auto? I also tried to wire it auto and ground direct to battery and manual to the switch wire in the harness, the pump will not come on with the switch and still blows the fuse on auto.

 

[Seastoke]

Have you tried them on the bench , with two batteries , I suspect one has polarity changed .

 

[QBhoy]

Hi. Couple things come to mind;
Are you using the original float switch ? Or is that In built to the pump unit ? If the former, it could be shorting out.
If the whole thing has been replaced, are the wiring arrangements as they should be ? No positive or negative wires conjoining somewhere to each other

 

[PhatMan]

I have checked what I can of the harness, partially run through the hull so can't check it all. As far as two batteries this is on my 12v system not my 24v. The float is internal on both pumps so it was changed with the pump. It just blows my mind that the manual override and the auto share a ground, and the manual works just fine on the switch but the auto pops the fuse as if it's shorted. Going to put the meter on it this evening and see what I can find.

 

[Seastoke]

What Iam saying you are using two batteries on the boat , to feed the pump is that correct .

 

[PhatMan]

Oh, no it is on a single battery system, the only thing on my 24v system is my trolling motor and garmen equipment.

 

[DavidJ]

I don’t suppose you have a second bilge pump somewhere which is connected in a way that they both come on in one signals. I haven’t heard of this set up but just clutching at straws.
The buzzer shorting out maybe although that would show on manual operation.

 

[PhatMan]

Idk, I'm at a loss, I took my meter and tested polarities and grounds and everything else you can think of. I'm honestly over it, I get 12v from the manual switch, and the same 12v from the battery I'm wired to. I think I'm just going to put both pump in and wire one straight to the battery just for auto bilge and the other only on the switch. Thank you all for your input.

 

[DavidJ]

Suggest inline fuse to your straight to battery connection

 

[PhatMan]

I will put one on the direct connection, the switched has a breaker at the panel. This is just crazy though, I don't understand why the same 12v from the switch and battery with the same ground are acting different. I really do appreciate all the input guys, it's helped me talk through this but I'm affraid I'm going to have to take it to the shop if I want it to work as it did factory, for now I'll just double the pumps up and use a check valve so I will have the manual for backup in hopes that the auto does not fail.

 

[BruceK]

My guess is the auto positive wire is internaly corroded or damaged at some point. The fact it delivers 12V is irrelevant if it has to pump up the amps to do the work because of the damage. You are tripping on amperage, not voltage.

 

[PhatMan]

I've not considered that, but the auto pos wire is all new, I pulled the old inline fuse and replaced the entire line, now that's not to say the ground isn't corroded somewhere in the system, I'll check that this evening thank you for altering my thought process, I've been hyper focused on that one wire.

 

[Seastoke]

Can you draw the circuit as you see it so we can study, not finding a fault is not good practice. Just say your boat caught fire , the insurance know you have issues.

 

[PhatMan]

I've checked what feels like every ground on the boat, all other electronics work as they should, it is the lonely power wire direct to the battery that keeps failing. I'll send the wiring diagram later today when I'm home from work. Not sure if I mentioned but it's an aluminum boat, the short I feel could be anywhere at this point. I guess the real question now is if the manual and auto share a ground, and both are 5amp protected why does the switch work, and not the auto that is wired directly to the battery with all new wiring. I promise I'm past frustrated with this and appreciate all the insite.

 

[QBhoy]

I've checked what feels like every ground on the boat, all other electronics work as they should, it is the lonely power wire direct to the battery that keeps failing. I'll send the wiring diagram later today when I'm home from work. Not sure if I mentioned but it's an aluminum boat, the short I feel could be anywhere at this point. I guess the real question now is if the manual and auto share a ground, and both are 5amp protected why does the switch work, and not the auto that is wired directly to the battery with all new wiring. I promise I'm past frustrated with this and appreciate all the insite.

To answer the question around why it works from one and not the other, with the thinking that they take from the same place…I’d say that its maybe not totally accurate. The helm manual switch surely takes a positive from a different route. Fed from the helm array. The auto is direct from the battery usually. Do you have a brown wire and brown and white wire ? With the brown to manual and the brown and white for the auto ? That’s what might be the usual or common at least.

 

[PhatMan]

Here is the wiring diagram for the boat if that helps.

 

[Seastoke]

Ok do you have a clip on amp meter , dc no ok. So am I right it’s a circuit breaker on the manual and fuse on the auto.

 

[PhatMan]

Yes I have a few different meters that will allow amp testing, and yes the switch is a breaker and auto is on a fuse. I'm going to go back at it this evening with a clear head but I'm open to any suggestions you might have.

 

[Seastoke]

Yes I have a few different meters that will allow amp testing, and yes the switch is a breaker and auto is on a fuse. I'm going to go back at it this evening with a clear head but I'm open to any suggestions you might have.

Ok swap the the brown wires at the pump operate the auto which is now fed via the circuit breaker, I recon it will work , just a min don’t connect the brown from the battery just the one from the switch. I feel the fuse is not a antisurge fuse. Now you did say it worked off the switch ok if so do what I said . Sorry for my English .

 

[PhatMan]

I actually did that yesterday and it will work the pump off the switch if I wire the auto to the switch and test the auto without blowing the fuse. The auto will also work if wired directly to my rear battery and not use the ground in the wiring harness. This is just very frustrating, I'll figure it out at some point, and if I do I will let everyone know what I found.