This is a 1st. I can honestly say I have never seen a problem like this. Tom is right, you need to talk to your friend dude. If it don't run for him, but runs for you, he will be suspicious. I was going to say install a battery Isolation switch under your seat, but this is something you need to talk out.
Regards
Dr. Phil Electrics
**Working PART-TIME for Carjunky for a while, Please bare with me =)**