Focus won't start

Get a new battery - go overkill on spec if you have a diesel too. My Diesel Pug is 10 years old and the sheer torque out of the starter motor (Original battery) is awesome. Diesels need to compress the gas and fire up the ignition system - it takes juice. Make sure EVERY other electric system not essential is off too.
 
Mk1 Focuses have a very easy to trip fuel pump breaker. I don't think they removed it from later versions. It may also interrupt attempts to power the starter - I can't recall off the top of my head. It's on the right side kickpanel in the US - I don't know which side it's on in the RHD configuration.

At any rate, it's explained in the owner's manual in the "OMFG MY CAR WON'T START" section.
 
Top