Electrical problem help

JDaPP

Adventurer
I have a 2012 JKUR with a genesis dual battery system. Currently has two Walmart regular car batteries. My issue is I have two auxillary tanks with pumps that are not working consistently. Did work fine for approximately 6 months.

Pumps are standard 12v fuel transfer pumps. One is wired to a Long range automotive dual fuel indicator / pump switch. The other is to a standard toggle switch. Both are than wired to a standard toggle that serves as a master power switch. Master power switch goes directly to main battery (both positive & negative). Sometimes works fine, some times will start and then just stop (almost like it runs out of power) and sometimes it just won't come on at all. I have checked connections and they seem to be tight (internal switches done with wire nuts, external wires to battery have crimped and waterproofed connectors with a positive line that has a inline fuse). No consistent time that it happens although seems to consistently fail when on interstate at higher speed but fails fewer times at slower speeds. Any thoughts?
 
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luthj

Engineer In Residence
Say it with me

Wire Nuts should never be used on anything that moves (or gets wet).

Replace the wire nuts with waterproof crimped butt connectors (or equivalent) and retest. If the problem still exists, get your volt meter out, and start looking for voltage drops in the wiring. Anything more than 1/10 of a volt for a connection is a problem!
 

JDaPP

Adventurer
For the wire nuts let me clarify, switches are internal to vehicle and have wire nuts, everything that could be exposed to water has been crimped and waterproofed. Will still change them out and see if that has an effect, hadn't really focused on the wire nuts because the setup did work for around 6 months before it gave me issues. Thanks.
 

luthj

Engineer In Residence
It very well could be something else. I have personally seen wire nuts pull loose on numerous occasions. Especially with stranded wire.

My voltage drop suggest still holds. Replicate the problem, and test for them.

Sometimes pump commutators develop a dead spot, but that usually keeps them from starting, and doesn't affect them after they are spinning.
 

luthj

Engineer In Residence
The ’ol ”Catch 22”...
Seal up all the connections, then try to measure voltages.
Yeah, I like needle probes. But you can also backprobe many connection types.

I will add to the OP, that you can test for the bad connection with your voltmeter before you start changing things. If you are pretty certain the nuts are okay, this may be the best option.
 

Superduty

Adventurer
Bad connection somewhere is my guess.

FYI - Wire nuts have NO place in automotive applications. I hope a professional installer didn't use wire nuts. Wire nuts indicates to me someone didn't know what they were doing. I would re do all connections.

Sent from my SM-G973U using Tapatalk
 

shade

Well-known member
Photos?

Since the wire nuts should make this easy to check, try bypassing the switches and see how the pumps perform.

Then get rid of the wire nuts. :)
 

JDaPP

Adventurer
Ran the pumps for 10 minutes in the garage and they stopped and started several times without me touching anything. I changed the wire nuts after that and moving the wires from the toggle switch would cause it to cut out so I am thinking a bad switch but going to do some more experimenting first.
 

JDaPP

Adventurer
Checked the fuse and it looked good, didn't feel it while it was going for heat will try that next time. Switch was not hot.
 

shade

Well-known member
What I usually do with this kind of problem is isolate the consumer from everything and just see if it's working right in the first place. Disconnect a pump from all of the existing wiring and run it directly off of a jump pack, or make up a temporary line between a battery under the hood and the device. It could be that both pumps are simply dying at the same time in their life cycle.

I'm not sure how you have the pumps grounded, but that's another common fault point, especially if they share the same ground.

As stated in the OP, the master power switch is another common point of failure to examine.
 
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