An Electrical Mystery or is it?

[CapetaniosG]

The bilge pump in the Generator compartment of my 53 Hatteras M/Y needs replacement. When I connect the volt meter to the two wires It reads 35.5 volts. When I hook the wires directly to the Rule 2000 pump the pump (band new) fails to operate. When I hook up the pump directly to the batteries the pump works fine. Can some electrical Guru explain why? The pump is 32volts.

 

[krush]

You have a bad connection and are falling victim to the trap that many people do when troubleshooting with a voltmeter.

Try using a test light.

The meter does not draw any current, so it shows the voltage. But when you put a load on the circuit, the voltage drops to zero.

How? Imagine only 1 tiny strand of copper is making the connection in your circuit. With no load, you will read voltage. But the second you put a load on it, that little strand of copper can't flow enough electrons for the load.

So I repeat, go back and use a test light to diagnose.

 

[Pascal]

When you say “when I connect the meter to the two wires”, which wires are you talking about? The wires going to the pump? To the float switch? Does the pump work in override / manual mode?

It sound like a wiring issue. Original non tinned wire? Terminal block? Shrink tube connections?

 

[racclarkson@gmail.com]

Float switch

 

[Boatsb]

Voltage can drop with amperage draw on poor wire pretty fast. Krush is right. Psychotic, but absolutely right. We gotta take these bastards. Now we could do it with conventional weapons that could take years and cost millions of lives. No, I think we have to go all out. I think that this situation absolutely requires a really futile and stupid gesture be done on somebody’s part.

 

[Oldlaxer1]

Voltage can drop with amperage draw on poor wire pretty fast. Krush is right. Psychotic, but absolutely right. We gotta take these bastards. Now we could do it with conventional weapons that could take years and cost millions of lives. No, I think we have to go all out. I think that this situation absolutely requires a really futile and stupid gesture be done on somebody’s part.

What's all this lying around sh.t?
Let's do it!!!!

 

[t109a60]

Float switch

I'll 2nd this.........

 

[SKYCHENEY]

Maybe the old pump is okay. If its a wiring/float switch problem, you may be replacing a pump that doesn't need to be replaced.

 

[oscarvan]

I'm with Krush. Happened to me more than once. Usually boat, sometimes cars. Corrosion is the usual culprit. Put a KNOWN working something on there with a decent draw. (Another pump) Even a test light may not be enough. Usually the ground is bad btw.

Confirmation will, of course be to take the pump and hook it directly to a battery... Look: It works!

 

[davidwigler]

I just replaced a bad float switch. Easy to test, just cross the wires to the switch and the pump should run.

 

[Pascal]

Bilge pumps should be installed with override manual switch and two power sources, one for the float switch and one for the manual switch. That makes it easy to test the pump va the float switch.

 

[CapetaniosG]

Thank you all for your input. Krush was right. Bad wiring. Connected directly to the battery (Switch and fuse) and the pump is pumping.

 

[Pascal]

Amazing how often I ve seen poor bilge pump connections incl butt connectors without shrink tube or worst... those Home Cheapo twist caps. And connections dangling too low in the bilge.