1998 Ford Explorer Sport V6, 2wd, manual trans, 150,000 miles. Lately i’ve been hearing a humming sound coming from the engine when i’m stopped. The sound goes away when I start to accelerate. Doesn’t seem to be a problem in cold weather. I’ve recently changed the radiator hoses and i know my upstream 02 sensors need replacing. I’ve heard this may be a fuel pump problem. Thoughts?
The fuel pump is located in the rear of the vehicle–on the gas tank–so a noise coming from under the hood is unlikely to be fuel pump related. Have you checked the exhaust heat shields? While heat shield noises are usually more of a growl or a rattle, it is possible that this could be something as simple as a loose heat shield.