Strange Water Pump Issue

[ktgsmokey]

Our 2011 FC 30' has developed a unique water pump issue and would appreciate anyone's counsel. If plugged into shore power it works fine. When running on battery power, it also works fine, except it continually stops working and if we turn the pump switch off for a few seconds (sometimes have to do that several times) it again works. It might work fine for an hour or might do this intermittent behavior every five minutes - no consistency. When it does run, it runs fine. I did notice that the pump motor itself will sometimes (not aways) get extremely hot to the touch when doing this even though the water jacket is cold and has water flow. Wondering if it is some type of 12v electric connection issue. First thought it might be a faulty pumps switch on the wall, but it does not falter when on shore power, so that would eliminate that as the culprit.

Anyone else ever experience this problem, and if so any solutions?

Thanks. Kim

[moosetags]

Actually, the fresh water pump always runs on 12 volt DC. The only difference when the trailer is plugged into shore power is that the pump is getting its 12 volt through the converter. That makes your issue even more mysterious.

All I can think of is a possible battery issue. When the pump is getting its juice directly from the battery, it may not like the juice it's getting.

Brian

[Skater]

My guess is you have some sort of 12 volt system issue, and the water pump is just a symptom of that. I really don't know, I haven't heard of this problem before, but as moosetags said, the pump always runs on 12 volt power, so the only difference between being plugged in and not is the voltage and the current available when the converter is on. I'd get out the multimeter and check voltages with the camper plugged in and unplugged, and with the pump running and not (so, four readings).

[drboyd]

Here's my guess:

Your battery isnt getting fully charged, or for some other semi-mysterious reason, the voltage at the pump is low. This causes the current to go up, which is tripping a breaker. An alternatate version is that there's a thermal protector in the pump motor that's tripping when the motor gets too hot.

Could be traceable back to your converter, or wiring.

Checking: Measure the voltage at the pump while it's running on the converter, and while it's running on the battery. If there's more than - say - a quarter of a volt difference, that's where to start.

[TG Twinkie]

Check/clean the connections at the battery terminals. It sounds like you have a voltage drop problem. ie corrosion at the terminals.


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[ktgsmokey]

Thanks for all the quick replies and counsel. Everything other than the water pump (tv, fans, lights, jack, etc.) all run fine off batteries, so sounds like the culprit may be a connection solely serving the pump. Time to get out the meter and do as drboyd suggested. Many thanks.

[jrswann]

I have had this issue on a 2013 FB FC. I would bleed the suction line and things seemed to work again. I'll look at voltage next time.

[moosetags]

Originally Posted by ktgsmokey

Thanks for all the quick replies and counsel. Everything other than the water pump (tv, fans, lights, jack, etc.) all run fine off batteries, so sounds like the culprit may be a connection solely serving the pump. Time to get out the meter and do as drboyd suggested. Many thanks.

Please let us know the outcome when you get to the bottom of this issue. We would all like to know for future reference.

Brian

[Jacob D]

You may have a bad battery. Check the voltage across the battery terminals with the terminals disconnected. A good battery should give at least 12 volts if it is fully charged. Voltage across the terminals while charging should be at least 12 3/4 volts but probably no more than 14 if your Univolt or Intellipower or whatever charging system you have is working correctly. Your water pump will probably run on as little as 8 volts but at lower than standard voltage will get hot. If it has an internal thermal overload it will shut off when it gets to the critical temp. Depending on how it is set up it may restart itself when it cools off enough but some thermal overloads have to have power off then back on to restart.

[ktgsmokey]

Thanks all. Definitely not the batteries since I just install two brand new, fully charged batteries before our trip two weeks ago, and the situation was the same as last year with the other batteries.

JacobD's comments strike a cord since I did note the pump motor (not the water jacket) getting extremely hot this time, so a thermal cutoff might be happening, although the reset is very quick and long before the motor cools down. I need to check the voltage it is getting which I will do this weekend. I'll let everyone know once I figure it out.

Many thanks.

[ktgsmokey]

Put a meter on the batteries and on the water pump at the converter this past weekend. 13.5v+ on batteries disconnected, and about the same reading at the water pump measured at the converter with shore power connected. Drops to around 13.25v at the water pump while pump is running and being connected to shore power. Drops to a little above 12v at the water pump while pump is running and disconnected from shore power. Not sure what that tells me other than it does not seem to be a voltage issue at the pump unless the 1v drop when not connected to shore power is the issue since the problem never occurs when connected to shore power.