Hi there, I am new to this site. I have a 99 Silverado 2500 6.0 with 66,000 miles. I am looking for any suggestions on this problem. I came out to drive my truck this morning and started the engine. I immediately noticed a humming that I hadn't heard before. I drove the truck a short distance with the continued humming. I pulled over turned off the motor and took the key out. The humming was still there and louder than ever. I immediately turned around for home and took the truck back. Once home, I turned the motor off again and climbed under the truck and it's coming from the fuel tank. I disconnected the battery cable so as not ti kill the battery. I looked up online and found that most likely it was the fuel pump relay stuck on. I immediately went to parts store and installed a new one. It is still humming without the key even on! I disconnected the battery cable again. What is next????? Thanks.

 

Did you check to see if the humming was there when the relay was out? Check the wiring for shorts. Look for any frayed wire or bare wire that may be touching something else. Could be anywhere from the fuse box back to the fuel pump.

 

Ok, new info. I was totally wrong. Yes, the humming was on when the relay was out. It is not the fuel pump, but it is the ABS pump. I did end up unplugging it, so it has stopped. Any ideas what has caused this? What it will cost to fix? Is it bad for the truck for me to drive it unplugged? I realize that my ABS is now non functioning but the brakes seem to be working fine anyway........

 

I may repost this with new title so as to maybe get so more opinions from people with this experience.