Sump - float switch and pump troubleshooting

[brianc]

New update...it's not working!

After a week of sitting unused, I turned on the power to the pump and the amp meter jumped but the pump didn't run. We were not on shore power but I tried it with the engine under load and then again back on shore power...same result. I reconnected it directly to the batteries and after a couple times touching the negative post on the battery it came to life and of course now runs when hooked back up normally through the float switch, etc.

I took some resistance readings today, but I need some help trying to interpret them, whether or not they reveal anything.

First, new pump out of the box vs installed pump. The reading on the new pump on 'auto range' (Amprobe 510 multimeter) was 037.6 and the installed pump was 000.3. I didn't see any indication other than the ohms symbol on the meter that the range was different between the two readings. Do those make sense if the installed pump is shorted (I thought it would read 0)?

I then turned off the battery switch but turned on the sump breaker and actuated the float switch and the reading at the wires that would be connected to the pump was 179.6, which doesn't seem right. The pump draws 8 amps but if that were the correct resistance number, the pump wouldn't get anywhere near that.

Volts at the battery was 13.8 and with the + probe connected to the + wire and the negative to the battery post it was 13.77. Does that indicate a problem on the negative side of the circuit? I did not check the volts connected to the negative wire, just the battery post.

Anyway, I thought I was getting somewhere with my troubleshooting ability, but apparently not. Any help would be greatly appreciated!
-Brian

[brianc]

I found the ranges for the meter. It looks like it selected the lowest for all the readings.

400.0Ω 0.1Ω ±(1.2%+2dgt)

[brianc]

Possibly the last update...

Last Wednesday the pump wouldn't run when I actuated the float switch so I cut the wires at the pump and measured the voltages...everything checked out. Voltage at the battery matched what was at the pump leads. So I did the usual and connected the pump directly to the batteries and after a couple "jolts" (touching the negative lead to the negative battery post) the pump came back to life. I was out of ideas so I went back today to replace the pump. When I re-connected the pump leads to the pump, the ****er ran normally. I re-measured the voltages and again, battery voltage matched the voltage at the leads. So I replaced the pump.

The new pump is installed and running normally as of this afternoon. I'll be happy if this is the end of it, but I'm not getting my hopes up.

Brian

[boatbod]

Sounds like bad brushes or pump motor. Replacement was the best option.