NC Engine cranking with key in AUX position until starter fuse blows

Technical Area Engine, Transmission, Exhaust etc
1
  1. My model of MX-5 is: __NC 1.8
  2. I’m based near: __Somerset
  3. I’m looking for technical help or recommendations on: __
    ENGINE fuse blowing and engine cranking with key in AUX position

Hi all. I have posted this up previously as a no crank no start issue. But that’s not what’s going on - so I am reposting the issue in a different way.

I changed my NC’s engine and when I connected it all up - and turned the key to the AUX postion (that is the first click - not the starter click) the engine suddenly cranked for about 4 seconds before blowing the 15 AMP ENGINE fuse. Then it would stop cranking.

I’ve looked at the switch - all seems fine - and I think it is working as it’s obviously sending a signal - even if it is at the wrong time.

I don’t think it’s the actual starter - as it cranks when the fuse hasn’t blown - and even if it was stuck on it would crank for more than 4 second - until I pull the earth on the battery.

As the ENGINE fuse is blowing it must mean a short. Perhaps the harness was pinched when I fitted the engine. I can only think my only option now is to drop the engine again so I have proper access to the wiring harness - particularly around the starter.

Any thoughts would be gratefully received before I drop the engine - again.

Cheers

Adam