This might be an answer I don't really want to here, but here goes. The other day I jump in the Jimmy and start her up and hear a humming noise from the rear. Heard it when I got to my destination and it stopped the next time I started the truck and brought her home. Tonight I could hear it again. I assume the only thing that could hum from behind the drivers seat.....is.....a fuel pump. I turn the key on and it turns on for a few seconds like it is supposed to. I started the truck tonight and I could hear a humming noise. When I got home I put my head under the rear passenger door and I think that is the humming I hear, which is where the fuel pump is. As I moved forward towards the engine I couldn't hear it anymore....so my question is...should I be worried....truck seems to be running just fine....but I am fairly sure the humming is the fuel pump running. The temperature has dramatically changed and dropped here over the last few days when this all started...so again...what to do...is this signs of a failing pump.

 

I wouldn't doubt it's your fuel pump, but to try to help it pick up some gas line anti-freeze and I'd recommend grabbing some of that fuel injector cleaner you put in your gas tank, it may help get any gunk out of your fuel lines as well as cleaning the injectors which may be causing your fuel pump to run harder than it should. Are you using cheap gas or the good stuff?

 

If it is the fuel pump....it shouldn't be running all of the time should it? After it primes and gets the pressure up it should turn off right? If it is the fuel pump it is running continuously as far as I can tell....

 

No your fuel pump shouldn't be running continuously, but really the only way to be 100% sure it for it to either die or to actually stick your face beside the pump. If you have ran your tank low or anything though it will screw with you pump as the fuel is the natural coolant for the pump. As well cheap gas may lead to killing the lines, messing with the pump as well. All the fuel pumps I have changed outare mainly due to them being over worked and the like and I have had a few people hear the fuel pump running continuously before it dies.

What year and model do you have?

 

It is a 1997 GMC Jimmy 4x4 4dr.

Is there a way to maybe start the truck and if I hear the humming pull a fuse or something to stop the fuel pump to see if that in fact is it?

 

The only problem with that would be that it may set off a code and turn on your engine light.I don't exactly know on a '97, but it'd most likely be a relay.

 

Check out the 'Fuel pump keeps running" on the 2nd page of this forum, same thing happened to someone else, doesn't look like it's been resolved though

 

That is the one thing that leads me to think it might be nothing or something else causing the thing to run like that. When I turn the key on I hear the fuel pump run then turn off...so it isn't sticking there if that is it. It runs then turns off like it should. IF the fuel pump is running only when the truck starts...shouldn't that cause some type of engine issue? What would cause it to run continuously only when the truck is started....relay?

 

I don't see this topic...

I think my fuel pump runs continuously as well when the truck is running... How else does fuel get from the gas tank to the engine?!??