I beleive one is for ignition system, the other runs the fuel pump. If they're humming, then I guess one might be crook and sucking the voltage down. Try replacing them, you might be pleasantly surprised. I've had to replace one of mine twice in the last 12 months, they're just poor quality. <img src="/forums/images/graemlins/cheers.gif" alt="" />

KIA, More dirt for ya dollar! 99 Sportage, Pod filter, Bosch Super4 plugs, electric thermo fan, racing pedals, Narva 100W driving lights, Yokhama 235/75R15 Super Diggers....getting to the rest bit by bit.