I have a whine your can really hear it while parked...it sounds like its coming from the rear end, could this be my fuel pump??

Heres my video with the new muffler and can hear the whine
YouTube - Flowmasters 40 series ford bronco

 

That doesn't sound like the fuel pump (to me), sounds like a loose bolt vibrating really fast (to me). I would get under the truck, engine on, to see if i can pinpoint the cause, of course, take all the safety measures necessary.

 

Could be the pump but honestly sounds like a vapor return leak or even a leak in the filler neck. (Air coming into the tank as fuel is removed). Hard to be certain.

 

Yeah i dont think its a loose bolt. Ive watched other videos of broncos and some i could hear the same thing... Think its something i should worry about?

 

DID YOU USE EXAUST CLAMPS

 

I did but that sound was their before I put a new muffler on it

 

Try running the fuel pump with the engine off. Then if you hear it, you could get right up on it to confirm.

Put somebody sensible in the driver's seat, windows down, door closed. Have them turn the ignition switch to ON, not all the way to START. The computer will turn on the fuel pump, but after a couple seconds of no distributor pickup pulses (because the crankshaft isn't turning), it then turns the pump off. To reset and try again, turn key to OFF, then back to ON.

Listening to the video, I thought it sounded more air-leak like, as grey did. But if it was a makeup-air restriction in the gas tank venting system, I would have expected the sound to continue a bit after you turned the engine off. But I was surprised when the sound died the instant the engine was turned off.

If running the fuel pump with the engine OFF does NOT duplicate the sound you are after, you could try starting it up, verify that the sound is still heard, and then with engine running, take the gas cap off and see if that has a major effect.

 

I think its that fuel pump. When i hear the pump prime with the truck off it sounds similar to the whine. I ran the truck and took the gas cap off and there was no difference.

 

Usually the fuel pump never changes speed as it maintains pressure. I could hear the pinch change from the pump starting up to the truck running, as if the pump kicked into high gear. That sound is unusual though...

 

Yeah im not gonna be surprised if it craps the bed one day