The other day I was driving my Z when it randomly shutoff. Suspected it was the fuel pump, replaced the fuel pump and the problem Persisted. I diagnosed that it was the ecm fuse so I replaced it and was able to cradle it home 3 fuses later. Now the car won’t even start without the fuse immediately blowing. I checked the o2 sensor wiring to see if it was grounding out but they all looked fine. Any ideas?

2005 350z 259,XXX miles

 

I'd unplug the o2 sensors and try again. Otherwise no idea.

 

What amp fuse does it call for and what amp are you using? Check your install and any grounds that aren't connected. This is a good time to buy/borrow an inexpensive multi tester.