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Fresh Water Pump
Got back from a trip to the Washington coast and a couple of days later was at the rig and turned on the water pump which promptly blew the fuse. So, I thought, since changing a fresh water pump on a MB is more fun that a barrel of monkies, I better buy a new one and get to it, so i did, turned on the switch, and voila!, another blown fuse!  So, I thinks to myself, I wonder if there is a wiring problem in that rats nest of wire, so i take out the pump, turn on the switch, and voila! NO BLOWN FUSE! But no water either.  So i hook up my handy multimeter to the pump to see if there is a short but nothing shows up, and if I hook 12 volts up directly to the pump, still nothing. I hate to think that a brand new Shurflow pump is defective, or am I missing something? Is there a good way to check out one of these pump before you do an installation? Advise please.  Thanks,
Ian Walker
2015 MB "Silver Fox"
Seattle
2015 MB
Re: Fresh Water Pump
Reply #1 –
Hi Ian,

It has been a while since I had to install a new water pump in our 2003MB. I seem to recall that there was an in line fuse on the wires for the last pump I installed. I would check to see if there is one installed on your new pump.

Is there anything else connected to that circuit? If so, perhaps a spice has gotten loose. Then there is the dreaded nest of wires heading to the switch in the range hood. Good luck.

Steve K
Steve K

2003 Mid-bath
Re: Fresh Water Pump
Reply #2 –
Ian, what I took from your post is that the old pump blew the fuse, then the new pump blew the fuse.  Then you hooked up 12v to the new pump and it did not run, but did not blow a fuse.  Am I reading that right?  If that is right, if you are sure that you are delivering 12v to the pump but the pump does not run, the pump must be bad.  So, use the multimeter, connect the wires to the pump but don't cover them, turn on the pump and check the voltage where the wires are twisted together.  That will help you determine if the new pump is bad.

With the pump removed, you turned on the switch and the fuse did not blow, right?  If you had a short it would not have been a hard wired short, because it had worked in the past.  Thus, a short due to wiring would have to be due to wiring that had chafed and was shorting, or something similar.  The process of removing the pump would have moved the wires, perhaps disconnecting a short that had developed.  I would start by turning on the switch and measuring the voltage at the bare wires that connect to the pump.  Then, watching the multimeter, wiggle and move each wire.  Then, lightly pinch each wire and slide it through your fingers, feeling for any damage to the insulation.

It's good to have a hobby.  This may keep you busy for a while.

Ken F in WY
'08 MB
Re: Fresh Water Pump
Reply #3 –
Hi Steve,
There is no inline fuse, just the 10 amp fuse in the panel which only blows when the pump is in the circuit and the switch is turned on. I have checked the wiring around the pump and found one spot that I did not like and have solved that problem.
I don't like their using solid rather than stranded wire in a vibration prone area as a failure could be nearly impossible to locate.
Thanks for your input!
Ian
2015 MB
Re: Fresh Water Pump
Reply #4 –
Hi Ken,

Thanks for your input. The fuse only blows when the pump is in the circuit and blows immediately. I have checked the wiring around the pump for abrasion etc. and resolved one possible problem area. I bench tested the pump by using my battery charger and multimeter.  Had  full voltage and continuity but no action, and was not shorted to the case. Any other way to test the pump?
They used to say, "It ain't over 'till the fat lady sings".  Now, it's "It ain't over 'till the dam pump works"
My local yard it booked solid until Sept., so the ball is in my court. Right now trying to find out what their tech might opine so will really appreciate any thoughts you might have!
Thanks, and will chat with you later.
Ian
2015 MB
Re: Fresh Water Pump
Reply #5 –
You can always try to put a 12V light in line instead of the pump. then turn the switch on and see if that blows the fuse. if it does, then you know there is a short somewhere and the fun of tracking it down begins.
2001 MB
Re: Fresh Water Pump
Reply #6 –
Have you tried running the pump from another 12-volt supply?
That would answer the question 'is the pump bad?'.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fresh Water Pump
Reply #7 –
Ian wrote, "I bench tested the pump by using my battery charger and multimeter." It's not clear whether he meant the old pump or the new one.
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Fresh Water Pump
Reply #8 –
"I don't like their using solid rather than stranded wire"

That's very surprising. I've never seen solid wire used for 12 VDC wiring in a Lazy Daze. (It's bad enough that they use it for 120 VAC--I replaced as much of that as I could get to with stranded marine cable.)
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Fresh Water Pump
Reply #9 –
Quote from: Andy Baird  - 
"I don't like their using solid rather than stranded wire"

That's very surprising. I've never seen solid wire used for 12 VDC wiring in a Lazy Daze. (It's bad enough that they use it for 120 VAC--I replaced as much of that as I could get to with stranded marine cable.)

I don't remember ever seeing any LD 12-volt wiring in solid wire, it's always stranded.
Only the 120-VAC Factory wiring is solid.

Larry

Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fresh Water Pump
Reply #10 –
Ian, a battery charger may noit deliver the number of amps that the pump needs to run, even though it puts out something like 14 volts.  As Larry said, rather than using the charger, connect the pump to an actual 12v supply to test it.  You can follow Henness's suggestion to use a 12v light with the pump removed to check the wiring from the switch to the pump.

Ken F in WY
'08 MB
 
Re: Fresh Water Pump
Reply #11 –
Ian, this is another Ken. I wondered if the problem could be something stuck in the pump which would not allow the motor to rotate. I don't know if there might be access to the end of the motor shaft that you could try turning, just to be sure that it will turn. I strongly suspect that a "frozen" motor would pull enough current to blow the fuse. Just a thought.
Ken

Quote from: Ian & Jean  - 
Hi Ken,

Thanks for your input. The fuse only blows when the pump is in the circuit and blows immediately. I have checked the wiring around the pump for abrasion etc. and resolved one possible problem area. I bench tested the pump by using my battery charger and multimeter.  Had  full voltage and continuity but no action, and was not shorted to the case. Any other way to test the pump?

Ian
Former 2009 MB owner