I noticed that in my '87 XJ that I have no Ballast Resistor. My fuel pump is loud, and I have read that the Ballast Resistor was there to quiet it down. I can hear my fuel pump if I try to listen for it, but the engine noise drowns out most of it. BUT after driving for a while, especially if I am on the trails with no road noise the pump will gradually get louder and louder, until it is a real loud hum almost like a squeel but not a reeeeeeee squeel. Its more like a high pitched humm. When I first start and run I just hear the normal deep hum that goes like Murrrrrrrrrrrr. Is it my fuel pump going out.
Here is a pic of my fender with missing balast resistor
Here is a pic of my fender with missing balast resistor