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OX66 Blowing 80amp fuse when battery connected

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cb8296

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VX225TLRY - Cleaning up some shoddy rigging in my boat and ended up shortening the main power leads to the engine and re-terminating to the battery. Started motor and ran on the hose after I finished with no issues. Went on to clean up some other wiring under the dash and now no crank, no tilt/trim. Sure enough, 80amp fuse on motor is blown. If I jumper the fuse and even touch the positive lead to the battery terminal it wants to weld and sparks go everywhere and blows apart my test lead. Any ideas?
 
cb8296 said:
VX225TLRY - If I jumper the fuse and even touch the positive lead to the battery terminal it wants to weld and sparks go everywhere and blows apart my test lead. Any ideas?
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Blown fuses usually indicate a bad ground. Your attempt at jumping the fuse with subsequent arc tells me you definitely have no ground. You need to determine if indeed your ground lead from the cranking battery to starter is compromised. First check the connections at both ends, make sure they are free from corrosion. If good, meter test the ground lead for resistance/continuity. I'm guessing your problem is here. If not, it's possible the ground terminal on starter is bad.

All in all, I believe this is a ground issue from what you've described. You'll have to trace the ground from its source forward, find the resistance.
 
ClassicAQ said:
Blown fuses usually indicate a bad ground. Your attempt at jumping the fuse with subsequent arc tells me you definitely have no ground. You need to determine if indeed your ground lead from the cranking battery to starter is compromised. First check the connections at both ends, make sure they are free from corrosion. If good, meter test the ground lead for resistance/continuity. I'm guessing your problem is here. If not, it's possible the ground terminal on starter is bad.

All in all, I believe this is a ground issue from what you've described. You'll have to trace the ground from its source forward, find the resistance.
Click to expand...


What I found was a dead short in the rectifier/regulator.
 
ClassicAQ said:
Interesting. Which wire in the rectifier did you discover was proving the +/- conduit?
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The red/white pair coming from the 80amp fuse to the rectifier/regulator. With everything else b+ disconnected on the motor it was still arching when trying to connect the battery. Put the ohm meter between the ground on the r/r and that red/white pair and it shows a dead short. The second molex plug you see in the pic is for an aux. charging circuit in case the boat has a second house battery.

Rectifier_Regulator.jpg
 
Looks like you know your electronics. Great job finding the short so quick. Sometimes, more like most times, it takes forever.
 
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