Rear end noise increases with speed

Been thinking I was hearing a tire, or brake, or bearing or rear end noise as the speed reached about 55-65 rpm lately, there one day, gone the next. 89 Jeep, 4.0, 2wd, stock.

Then a few days ago I was hearing it at about 35-40 rpm. So I drag a jeep friend of mine over, we turn off all the noise distractions, AC, Radio, get up to up 60 mph and test drive it for a good 15 miles and nothing, na-da, not a hint of the sound. (NO it was not the radio or AC, LOL). I checked the diffy oil and it was fine, no leaks, brakes are fine......

Only thing I did before we test drove, just before he showed up, was I put 16 gallons of gas in the gas tank.

maybe the pinon bearing or wheel bearing is bad. i had the same thing happen to my zj. it took me a while to find out what it was.

Based on my current data, the only thing that makes any sense to me is that the fuel pump is noisier as it pumps more, and can be heard as an echo from a near empty gas tank, and then the re-fueled gas tank, liquid gasoline acts as a sound absorbent, killing the noise right after refilling the gas tank.

renix pumps like to make a hell of a racket when the tank gets low, especially if you've bypassed the ballast resistor.

GrimmJeeper said:

renix pumps like to make a hell of a racket when the tank gets low, especially if you've bypassed the ballast resistor.

Click to expand...

1987 vintage had no ballast resistor. It is an 87

"Rear end noise increases with speed"
Some peoples rear end noise increases with more burritos.
Sorry i had to say it

make sure the E brake cables are not rubbing on the inside of your rear tires.

Wallyman said:

"Rear end noise increases with speed"
Some peoples rear end noise increases with more burritos.
Sorry i had to say it

Click to expand...

Nice try, but my Jeep is not a people, it is a JEEP!!!assgas:

GrimmJeeper said:

renix pumps like to make a hell of a racket when the tank gets low, especially if you've bypassed the ballast resistor.

Click to expand...

The nice thing about the noise, is you know the pump is actually working on a cold morning no start, , LOL.