engine dies when fans turned on

i have one relay thats good for 30 amps running both of them. i do have a voltage meter mounted but not hooked up yet. i guess i need to get under the dash tommorrow and bypass that alter. gauge. its strange the engine dies as soon as i flip the fan switch , the battery is a good one , oh well i guess its time for an alternator upgrade .

Just for the sake of things ... have you slowly went over and checked all your wiring?

I would hook the MSD power wire straight from the battery (with it's proper fuse of course) and then throw the fan switch and see what happens.