Bad Tach or Tach wire?
 

Had an issue with the boat last week, we were just cruising along and motor just died. Sounded electrical and ended up being towed back to the dock. After I got home and did some troubleshooting I thought it was the shift interrupter switch so I swapped it out but the motor would still not start. I have both the shift interrupter switch wire and the tach wire going to the tach plug on my HEI distributor. So after some wire switching I found the tach wire or tach is grounding out the distributor. Since the tach wire goes through the main wiring harness I will be running a new wire and installing a new tach. Anyone ever have this happen?

i have seen a tach short out internally and cause the engine to shut down.

I agree ^^^

Tahoe, you have an Alpha ? Bravo's don't have a shift interrupter.

Thanks for the responses, and glad to hear this has happened. I actually have a new tach to match all my new gauges but it would not fit in my pod as it was 3/8" too long so I put the old one back in just to take it out and got bit by it. I actually have a King Cobra outdrive (yikes) and it does have a shift interrupter switch. It was not very easy to find a replacement. I have a spare now LOL.

the ignition system on the king cobra is junk,i replaced the one on my buddy,s boat with a msd ready to run when his crapped out.

Oh it does not have the stock OMC stuff. I put a marine DUI in it to replace the old 6a and rusted out msd distributor it had. It really only has the OMC wiring harness now and that has been greatly reduced now due to getting a factory manual that has saved me on wiring this thing.

I also have an old Livorsi speedo that didn't work and found this article so I will be fixing this too today too with a new tach. Livorsi GPS speedometer antenna fix for about $100

Well back out this week to see how she does on Lake Tahoe we still have not gone over 40 mph.

Not related to your problem, but did you run a dedicated 12g wire to that DUI system? I think the Merc wire is about 16g but I can't be positive as the op had a lot of fubared rigging that I had to redo. I switched out that 16g wire for a dedicated line off of a relay and it ran like an entirely different boat picking up about 500rpm.

Yes I did run a new wire (14 or 16 gauge) from the relay to the distributor. I have tried to replace all of the none factory harness wires.

unhook tack see if it starts

I did unhook the tach and it started right up. New tach installed (starts) and fixed my livorsi speedo with a new antenna. While I had the pods up I was able to polish the deck too.
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