Strange wiring problem with pumps

[tboydva]

OK, so I thought I might have figured this one out, but now I'm not so sure... I have two pumps (bait and bilge) on my boat. I just hooked them up after a over-winter boat restoration. I ran an 8 gauge service (+ and -) to the console and have 5 14 gauge service wires run (though the same conduit) to the stern of my boat to power the running lights, bait pump, bilge pump, aux pump and my duo-charge unit. My console has a distribution block with a + and - bus and a series of fuse slots to which I have my switches connected. I have a common ground going to each switch (ganged) and separate + wires running through each fuse to respective switches. All of my switches are lighted, so the + service wire goes to the middle tang while the wire going to the device goes on the "bottom" tang. This works fine for all my devices, except...

When I power on the bilge or bait pump, the other's switch light comes on very dimly? So, if I switch on the bait pump, the bilge indicator lights comes on dimly. Conversely, if I switch the bilge, the bait pump light comes on dimly. I'm attaching a wiring diagram so this might be a bit less confusing. I'm on travel this week with too much time to ruminate. I hooked each pump (Rules) per the mnfctr's instructions (black to (-) and brown to (+)). I was thinking perhaps that the wires might be put in incorrectly in one of the pumps, thus distributing the load across both the pump and light when either is tuned on. But, now that I think about it more, I guess the other lights on the other switches should come on under this scenario? I suppose I need to measure the voltages at the "other" switch when either pump is on to see if there is a negative potential? I'm really confused by this one. The wires run along the same conduit (and are tied together), but they are brand new and I cannot imagine them being bridges anywhere???

Anyone have any ideas??? Thanks!

 

[triumphrick]

Re: Strange wiring problem with pumps

Check your connections, especially the ground wires at each of the pumps. Usually when power is back fed like you are describing, the ground is gone or intermittent. Using a simple auto test probe, go to the common wire junction near the pumps and with both pumps disconnected, check for good 12v as switches are activated. Test light should light brightly. Also, the bilge should have an auto feature that can be confusing and could have an effect if crosswired or if shorting internally. Good luck.

 

[tboydva]

Re: Strange wiring problem with pumps

Judging from the indescribable things that can occur with trailer light grounding, I'm figuring that could be an issue. I usually coat all my connections with carbon conductive grease, but I ran out - perhaps the ground isn't "tight." I'll find out tomorrow. This has been messing with my head - I just got everything hooked up before having to go out of town! I'll post my findings...

Thanks!
Tom

 

[drewpster]

Re: Strange wiring problem with pumps

A few possibilities,
Bad ground paths. (check connections, test using ohm meter, use proper gauge wires)

Motors wired through light circuit in switch (be certain you wired the switches correctly)

Bad motors (power each motor individually without the switches in circuit, look for voltage on the ground side of each motor, if leftover voltage is on the ground side of a motor while it is running and the ground tests good, the motor is bad)

Junk switches (if you bought cheap switches be aware the primary and secondary circuits may not be isolated very well in the switch itself) I have had that problem before.

You could try grounding your pumps directly to the battery lug on the ground buss. You could also try to move the grounds of the switch lights to another ground point. When you check your ground paths, be sure to check the ground paths of the secondary circuits in the switches as well (lights).

It has been my experience with lighted switches that the cheaper ones tend to do this. Every DC motor circuit has a tiny bit of leftover voltage. No ground is ever perfect. The cheaper lighted switches tend to be more sensitive to this voltage. You should be ok if all your grounds are good and they are fairly isolated from each other.
triumphrick makes a good point about Rule pumps. Some Rule pumps have an auto feature in them. They come on at preset intervals for a second looking for back pressure. If they "see" back pressure they know there is water in the bilge and come on the pump the bilge out. This feature is generally only on the higher end pumps though. It eliminates the need for separate automatic bilge switches. Let us know what ou find.

 

[drewpster]

Re: Strange wiring problem with pumps

jjj

 

[tboydva]

Re: Strange wiring problem with pumps

Drewpster et al... OK, I figured it out!!! Almost too embarrassing to admit, but my "big" crimp (with the 6 gauge wire going to the ground in the console) came undone (or I didn't do a good enough job crimping it). So, that was the root of the evil. The pumps were grounded to the (-) terminal on the battery, but the switch grounds were floating! After much head scratching (and measuring voltages at the pumps), I finally decided to measure the voltage at the distribution block in the console. 0V!!! Did some tracing, then finally found the wire pulled out of the crimp (in my nice, carefully zip-tied bundle). Did too much cleanup I guess:

Thanks for the help and the tips... Being away for a week to ruminate wasn't productive I think!!!

 

[triumphrick]

Re: Strange wiring problem with pumps

Neat Job...like the ty wraps and clamps. That's the way wiring should be run. Good troubleshooting as well.

 

[DJ]

Re: Strange wiring problem with pumps

Very neat and clean.

However, I'm not a fan of "zip ties" on a hose that leads to an underwater fitting (bait pump). I prefer a stainless clamp.

 

[tboydva]

Re: Strange wiring problem with pumps

Thanks all! Did a water test today with great success! DJ, I'm with you on the hose clamps! I'm fresh out and I've spent far too much money this summer at McMaster-Carr and West Marine... Got the other side of the bait pump and drain to secure too! Next order will do it. Here's the crew going for a short ride:

 

[drewpster]

Re: Strange wiring problem with pumps

Good boat, great crew and a nice day, sounds like the makins' of a fun day! I am glad you got it worked out. Looks like the crew is always up for a boat ride.