fuse blows when swich off

Funny new problem, engine cut out for no apparent reason today, after getting a tow home and poking around a bit i found the 40A fuse for the starter motor had blown. replaced this and she started up fine, but when i turn her off this fuse blows again everytime.
Any of you electrical gurus know where i should be looking to solve this problem?

2001 4.6 on lpg

Fuse 40 (40A on 1999 on) also powers the EAS Compressor....

I would check both Relay 20 for the EAS compressor...if on switch off as it closes, it could shorting inside...

WIld shot in the dark but you never know!

thanks saint ill have a try in the morning. Could i try removing relay 20 and if thats ok then presume thats the problem and replae with a new one.

Removing relay 20 and your fuse not blowing would prove that your problem is on that circuit but I'd investigate a little further before you replace the compressor, starting with relay 20 and it's socket.

Put another fuse in and started her up and left it running while i had a poke around, swapped relay 20 over with another and still no joy.after it had run for a couple of mins a flash from the fusebox and same 40A fuse had gone. So with the info above i looked at the eas pump EAS pump wasnt running at all, now i replaced the seals in the compressor several months ago so disonneted the pump and put it across a battery, just a clunk and didnt run opened it up and the con rod to the compressor piston had completly sheared and the piston head just fell out. SO looks as if i have found my root problem. New eas pump on its way.

recon eas pump in and all seems well, fingers crossed.