Bilge pump blowing fuse on auto

[Seastoke]

I actually did that yesterday and it will work the pump off the switch if I wire the auto to the switch and test the auto without blowing the fuse. The auto will also work if wired directly to my rear battery and not use the ground in the wiring harness. This is just very frustrating, I'll figure it out at some point, and if I do I will let everyone know what I found.

But did you use the fuse

 

[PhatMan]

But did you use the fuse

Yes, left the fuse inline and it operated as it should

 

[BruceK]

Look for black wire rot in your ground then.

 

[QBhoy]

Ah. So it’s possible that something on the same earth route could be shorting ? I’d disconnect each of the other ancillary items on that shared path, see what happens.

 

[Seastoke]

you could run a negative from battery to neg block just touch on first in case there is a spark ( away from petrol ).

 

[PhatMan]

Little update, think I have identified the problem, seams I have a voltage drop from the ground at the harness to the battery, I read 12v at battery, 12v at wiring harness while pump is running, 10.2 from harness ground to battery. I have went through every ground and have yet to identify the correct wire but I'm on the right track. Again thank you all!

 

[Seastoke]

It could be the poz

 

[QBhoy]

Little update, think I have identified the problem, seams I have a voltage drop from the ground at the harness to the battery, I read 12v at battery, 12v at wiring harness while pump is running, 10.2 from harness ground to battery. I have went through every ground and have yet to identify the correct wire but I'm on the right track. Again thank you all!

Sounds like you’re definitely on the right track. Can I quickly ask around where you have the brown and orange wire (boat wiring side) conjoined to (on pump wiring side) or more specifically perhaps, to ask if there is no chance that there is a short between there and earth, by means of a fault…like the brown and orange wire somehow finding it’s own route to an earth, like bilge water or anything it may have tried to earth to close by ?

 

[PhatMan]

Sounds like you’re definitely on the right track. Can I quickly ask around where you have the brown and orange wire (boat wiring side) conjoined to (on pump wiring side) or more specifically perhaps, to ask if there is no chance that there is a short between there and earth, by means of a fault…like the brown and orange wire somehow finding it’s own route to an earth, like bilge water or anything it may have tried to earth to close by ?

Brown and orange is directly to the battery, I got it going today, I just pulled new wires to the switch and made my own ground and harness, it pumps as it should! Well no real answer on what it's doing but the wiring is so hard to get to I gave up and run my own.

 

[QBhoy]

Brown and orange is directly to the battery, I got it going today, I just pulled new wires to the switch and made my own ground and harness, it pumps as it should! Well no real answer on what it's doing but the wiring is so hard to get to I gave up and run my own.

Yeah. Saw it goes there, but was wondering if it was shorting to it’s own found earth path somewhere in the bilge.
Anyway..sound like you’ve got it under control. Excellent news