Blown water pump fuse

[HC Dan]

Have a situation in the middle of a 14 day trip in a 2016 international 28’
We started our 500 mile trip home yesterday morning and when we stopped for the evening had blown the 15amp fuse that runs the water pump, tank monitors and battery voltage display. I had a spare and we spent the night with no problem. When we arrived at our destination this evening same fuse blown. We had to fill the fresh water tank because we will be here for 3 nights. And changed the fuse again before moving from the water source to our camp spot. Fuse was blown again when we parked a quarter mile away.
What I know:
1. I’m going to pull the fuse on the trip home because I’m running out of 15 amp fuses.
2. The trailer batteries show 12.7 volts not connected to the truck

[uncle_bob]

Hi

1) There is a pressure sensor on the output of the pump. It stops the pump before the pressure gets to high and the pump pulls to much current.

2) Crud in your fresh water tank can get into the pump and create issues, if the magic strainer is somehow missing in action.

3) Indeed pump motors do go bad .....

4) Wires chafe and short out.

That's a quick list. There are other possibilities.

Bob

[HC Dan]

Hey Bob, thanks for the reply. I got cut off before. The rest of what I know is that with the truck disconnected and turned off the voltage at the 7 way is 12.2 and when the truck is on it goes up to 14.6. I don’t have an amp meter with me. Voltage across the fuse is 12.6 when not hooked to the truck. Sitting in the camp site every think is working just fine, pumps, gages and all, but when I hook it to the truck when I am leaving I’m going to see how many seconds it takes to blow the fuse after my wife starts the truck.
While on shore power for 7 days the fuse was fine. And with the pump off the fuse blew while we pulled from the water spigot to the camp site. Disconnected the truck replaced the fuse. Everything working over night. It only has blown when connected to the truck. Which doesn’t exactly make sense to me that only that fuse blows if it is the truck overcharging

[HC Dan]

We are at Davidson River campground in Brevard NC. No cell service, primitive camping. The only time I can respond is when we go to town for something. Not an emergency, everything working till I hook back to the truck to go home. Just a brain teaser in a border collie type of guy

[HC Dan]

One more bit of information. When I got back to camp I hooked up the umbilical cord to the truck and left it running for 15 to 20 minutes with no blown fuse. Could not find a loose connection behind the tank switches or where the wires hook to the water pump

[AtomicNo13]

Low voltage = higher current draw and blown fuses. Charge up your batteries. I'm willing to bet you'll stop blowing fuses with better battery voltage.

[uncle_bob]

Originally Posted by AtomicNo13

Low voltage = higher current draw and blown fuses. Charge up your batteries. I'm willing to bet you'll stop blowing fuses with better battery voltage.

Hi

If the pump motor looks like a resistive load, lower voltage will mean lower current. It's not a very fancy gizmo so I'd bet that is the case.

=====

Has the screen on the pump been checked for debris? That's a lot more likely issue.

Bob

[HC Dan]

The water pump has never been turned on when either of the 3 fuses have blown. But it has been turned on ever since I parked in the camp spot 2 days ago with zero problem. Spoke with somebody at JC yesterday when I was in town. He was thinking short from loose connection vs the truck over charging. Movement + short out = blown fuse. Nothing in that Circut is in use when the fuse blows. Just bouncing down the road.

[uncle_bob]

Originally Posted by HC Dan

The water pump has never been turned on when either of the 3 fuses have blown. But it has been turned on ever since I parked in the camp spot 2 days ago with zero problem. Spoke with somebody at JC yesterday when I was in town. He was thinking short from loose connection vs the truck over charging. Movement + short out = blown fuse. Nothing in that Circut is in use when the fuse blows. Just bouncing down the road.

Hi

If indeed nothing is ever on then indeed you have a wire somewhere in the trailer shorting out.

Bob

[HC Dan]

There are 4 things that I know of on that circuit, the pump, the three tank monitors and the battery voltage monitor. Could I place inline fuses in each of those loops with maybe 10 amp fuses and sort out which on it might be? It’s going to involve doing something then driving around for an hour or two till something blows

[uncle_bob]

Hi

If you want to eliminate legs of the circuit, simply disconnect them.

Bob

[HC Dan]

Oops guess that’s five

[HC Dan]

The plop thickens, turns out there are two more legs to Circut #5 which are the direct and indirect lights in the locker above the couch. I tested continuity from downstream of the fuse to upstream of the light switches and water pump switch. Spoke with Airstream and the connections appear to be made in the main harness near the floor on the road side which is the monster bundle of wires taped together and covered with a corrugated tube. A poor connection is where they would start. I have access panels below the closet and below the stove but need access below the drawer stack and sink. There is a board which possible access with two screws under the drawer stack that seems to go all the way across, but seem to be attached from behind. Any ideas?

[uncle_bob]

Hi

A poor connection usually means a pair of wires that are a bit loose. That will give you an open circuit / no lights and not give you a blown fuse. What will give you a blown fuse is a wire end that is flopping around and hitting something that is grounded. That should be easier to spot. Indeed a wire that is worn through as it passes the edge of an aluminum panel is also a good bet ....

Bob

[HC Dan]

That is what I’m thinking too. I found my access point. Removed the plywood “seat” under the cushions on the L of the couch and the arm rest up against the sink cabinet and had good access to where the power feed from the fuse split into the three legs of that circuit. Two went up the wall to the seelevel panel and one went forward and ends up with another split somewhere feeding power to two light switches by the door. I placed 12 gage inline fuses with 5 amp fuses in them between the first split and where the head up the wall so hopefully when I blow a fuse I will know which leg to explore. Then today it was testing day. Drove on a two hour drive on back roads. Yes you guested it. No blown fuse. That would be too easy. I’m putting it to bed for the winter. Pitiful