Fresh water pressure pump wiring

My pressure pump for the sink/shower recently went out, and I don’t seem to have power at the wire to the pump now. I testing it with my multimeter between the red and yellow, but I get no voltage. The pump breaker is on and there is power at the breaker. Am I missing something? I don’t see an inline fuse anywhere, and I can’t see the entire wire run back to the breaker. It’s a 50amp breaker.

50 amps seems excessive. Sure you have the correct wire. Only other thought I can off is that on my system there is an external (not part of the pump) pressure switch. Maybe that's what went bad.

Ted

Run new wire to the pump. Easier than troubleshooting.

Or, run a temporary test wire from breaker to pump and determine which wire, red or yellow, has no continuity, with a multimeter.

cardude01 said:

My pressure pump for the sink/shower recently went out, and I don’t seem to have power at the wire to the pump now. I testing it with my multimeter between the red and yellow, but I get no voltage. The pump breaker is on and there is power at the breaker. Am I missing something? I don’t see an inline fuse anywhere, and I can’t see the entire wire run back to the breaker. It’s a 50amp breaker.

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Assuming this is a DC pump...Take your multimeter set to read DC volts and place the red lead on the red wire and the black lead on a good ground nearby. Do not use the other wire. See if you get voltage. If no voltage do the same with the red lead on the yellow wire just in case. See if you have any power on either wire using a known good ground.

Then set your meter to ohms and put the red lead on the yellow wire and the black lead on any good ground nearby. Same for the red wire just to see what you have. This checks for your ground.

That will determine if you have no power or no ground or maybe both. Once you find out which one you dont have you will have a better idea where to look.

You can also find both opposite ends if they terminate close, disconnect them from the terminals and connect them together. Then go back to the two ends in your picture and ohm it out. If it ohms out good then both sides of wire run are good...or not.

Dont forget you need a good ground to read any voltage or have any useful voltage.

First off that wire is way to small for 50 amps. Second, a 50 amp breaker is a big circuit breaker, not your standard flip switch in a panel.

I am guessing you meant 15 amp breaker. With that in mind you either have the wrong breaker or there is some form of a break in the line. Unfortunately you now need to follow the wire all the way back to find the trouble.

syjos said:

Run new wire to the pump. Easier than troubleshooting.

Or, run a temporary test wire from breaker to pump and determine which wire, red or yellow, has no continuity, with a multimeter.

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Did this with a temporary wire from the pump fuse block to check. Ground wire at the pump has continuity but red does not.

Found this fuse block behind the console. Thought I found the problem, but the damn fuse is good!



The 50 amp breaker feeds all of these pumps, each has a 15 amp fuse. So I guess that’s the reason for the big breaker.

I’m perplexed! How would a short have burned through the rather thick red wire and not blown this little 15amp fuse?

Some times the fuse element will detach from the end and the break is hidden under the end cap. Check voltage on each side of the fuse or try another fuse.

Probably a break in the wire. Or corrosion..

Easier to replace the red wire than to find break.

syjos said:

Probably a break in the wire. Or corrosion..

Easier to replace the red wire than to find break.

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Agree. Don’t think I’ll ever trace it down. Frustrating.

The red wire at the fuse block look different than the red wire at the pump. Can you confirm that the red wire at the fuse block goes into the grey sheathing with a red and yellow and that it is one continuous wire from the fuse block to the pump. Unless i could confirm that it is in fact a single wire with no other connections in between i personally would keep looking. There could be a local and separate switch. Thats actually a nice setup. I would be surprised if there was a corroded wire in the middle.

Also..what kind of pumps. Are they continous? On demand with built in pressure switch? On demand with external pressure switch?

Lepke has a good point. I've seen his suggestion a few times also.
Try a new fuse. I have seen fuses where the element bends enough to lose contact/breaks inside the cap and loses continuity. When the pump runs the element heats and bends breaking at the cap.
Have you confirmed there is a reliable 12V at the buss bar of the fuse block from the 50A breaker?
I have seen faulty C. breakers also.

C lectric said:

Lepke has a good point. I've seen his suggestion a few times also.
Try a new fuse. I have seen fuses where the element bends enough to lose contact/breaks inside the cap and loses continuity. When the pump runs the element heats and bends breaking at the cap.
Have you confirmed there is a reliable 12V at the buss bar of the fuse block from the 50A breaker?
I have seen faulty C. breakers also.

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I swapped fuses and checked for power on both sides of the fuse with good results.

If its hot to the fuse and your ground is happy there could be your problem. Between the fuse and the pump. Check all connections even the ground then re run a new positive wire if there is nothing obvious. I have a feeling there is a broken wire or bad corroded connection/crimp somewhere. If you feel daring get a toner and from the pump and trace it to the fuse.

I did not read if you tested the pump as well to be sure it is not on its way out causing it to pull more amps.

You got a good part of diagnosis done by locating the circut and fuses.

The old pump locked up and created a dead short. I had installed separate fuse at the pump and it blew that one. Then I screwed up and put in a bigger fuse and it popped that one.

But what I still don’t understand is why didn’t it blow that other 15amp fuse at that pump fuse block?

cardude01 said:

The old pump locked up and created a dead short. I had installed separate fuse at the pump and it blew that one. Then I screwed up and put in a bigger fuse and it popped that one.

But what I still don’t understand is why didn’t it blow that other 15amp fuse at that pump fuse block?

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So you are saying from the battery there is a 50amp breaker feeding the bus, then your 15a fuse there to the circut, and after that another fuse that was by the pump. What size fuse is there and what did you replace it with?

Id eliminate the last fuse keep the one at the bus. If you want drop it to 10amp if the pump does not pull that much.

Yes that’s right

The fuse right at the pump was a 15 amp, then I just grabbed a 30amp that was sitting there and it popped that one easily. Then I lost power to the wire.

I have removed that 15amp fuse at the pump. It was just there so I could leave the pump breaker on to run the other pumps, but shut off the power to the freshwater pump when I was away from the boat. It was a crappy setup but I just did it like that because that’s what I had on hand. Was planning on putting in a more suitable disconnect at the pump when installing this new pump, but now struggling with this no power problem.

30 amp should be no where in the circut with that guage wire. The wire could fail before the fuse blows. Do you have a dc switch sewhere for fresh water that you may of turned off past the fuse block? Or do you have a pressure switch inline to kick the pump on and off? With no pressure should be calling for water unless that has failed from overcurrent when the pump siezed.


Edit. Why the 30a fuse blew first, you may still have a short somewhere closer to the load or pump, I can not say without looking at it all.

So the power to your fuse at the pump was there to blow the 30amp fuse, but after that blew you didn't have power there anymore? Seems like the 30 amps did some damage. Very odd that the fuse at the buss bar didn't blow. Maybe the buss bar is not where the pump was getting its power.

mike66 said:

So the power to your fuse at the pump was there to blow the 30amp fuse, but after that blew you didn't have power there anymore? Seems like the 30 amps did some damage. Very odd that the fuse at the buss bar didn't blow. Maybe the buss bar is not where the pump was getting its power.

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Yeah maybe that fuse block is not labeled correctly. Every fuse is good on that block and has power on both sides.

I ran out of time to chase it down and had to drive back to Texas. Sigh.