have here a mk1 1.2 punto and the 40amp fuse in the engine bay fuse box keeps blowing. any ideas what its for and why its doing this?
many thanks

Only one reason a fuse blows, too much current going through it. 99% of the time it is caused by bad earth contacts on whatever the fuse covers. So start by looking at the earth connections and cables for signs of rust, salt water corrosion (green deposit on cables) and very stiff or brittle cables. Not insulting your intelligence but absolutely DO NOT put a larger fuse in! The only result will be a fire or destruction of whatever the fuse covers. What does it cover out of interest?

Does your radiator fan turn freely?

Good point if thats what the fuse controls. If it does and the fan is jammed or catching it will cause the motor to overload, blowing the fuse.

many thanks for your help. I've worked out its the ignition fuse. nothing activates when you turn the key. now the ignition barrel seems slightly strange to turn and has been slightly weird like slightly resistant to turn. its been kinda weird for a while, so if its packed in would that blow the fuse?

it could be shorting out inside

ok, so today, unplugged most things, and its still blowing the fuse. I also pulled all the fuses out of the fuse box and out the relays on the passenger side. it still blew. it only didn't blow when had the top connector out the ignition barrel (not the one with the big red wire), also the browny looking wire going into that connector looks slightly frayed but isn't touching any other wire, but the plastic connector only around the wire is all brown as if its slightly burnt.

Does sound as though you've found the fault. Check that nowt's burnt through further down the harness. If you can find a barrel and key at the scrappy you can fool the imob by taping the old key close to the barrel.

fingers99 said:

Does sound as though you've found the fault. Check that nowt's burnt through further down the harness. If you can find a barrel and key at the scrappy you can fool the imob by taping the old key close to the barrel.

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are the barrels hard to replace?? and the wire just goes straight to the engine bay fuse box then straight to the starter motor, so won't be the starter will it?

You could test the starter directly by briefly jumping to a 12v battery. If it turns, it's very unlikely to be the starter.