Electric Motor Sound From Rear Of Bronco

[brilltastic]

I was getting out of my Bronco the other day and heard, what sounded like, an electric motor coming from the right rear wheel. I do not use my emergency brake, so it shouldn't be that. A few days earlier I did hear a horrible screeching noise coming from under the vehicle while driving on the highway. It lasted 10-15 seconds and has not happened since. Any thoughts?

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[jsteph262]

Could it maybe be the fuel pump? I know there have been a few cases of those going bad, not sure if they had similar symptoms to this though.

 

[JediMcMuffin]

I was getting out of my Bronco the other day and heard, what sounded like, an electric motor coming from the right rear wheel. I do not use my emergency brake, so it shouldn't be that. A few days earlier I did hear a horrible screeching noise coming from under the vehicle while driving on the highway. It lasted 10-15 seconds and has not happened since. Any thoughts?

I am fairly certain the parking brake will engage automatically. It doesn't sound like a screech to me, just a whirring motor.

 

[Jimmiee]

What you were hearing was probably the EVAP Leak Detection Pump. Here's an overview of how this works:

he EVAP leak detection control module consists of a vacuum pump, a pressure sensor, a 0.02" reference orifice and a switching valve. The vacuum pump is used to apply a vacuum across the reference orifice and to apply a vacuum on the EVAP system for the EVAP leak check monitor. The 0.02" reference orifice is used to obtain a reference check for leak detection every time the EVAP monitor runs. The pressure sensor is used to determine the vacuum level across the reference orifice and for the EVAP leak detection monitor.

The EVAP leak detection control module is vented to the atmosphere through the switching valve and allows for purging during engine operation and refueling.

 

[brilltastic]

What you were hearing was probably the EVAP Leak Detection Pump. Here's an overview of how this works:

he EVAP leak detection control module consists of a vacuum pump, a pressure sensor, a 0.02" reference orifice and a switching valve. The vacuum pump is used to apply a vacuum across the reference orifice and to apply a vacuum on the EVAP system for the EVAP leak check monitor. The 0.02" reference orifice is used to obtain a reference check for leak detection every time the EVAP monitor runs. The pressure sensor is used to determine the vacuum level across the reference orifice and for the EVAP leak detection monitor.

The EVAP leak detection control module is vented to the atmosphere through the switching valve and allows for purging during engine operation and refueling.

Interesting. where is that pump located?

 

[brilltastic]

I am fairly certain the parking brake will engage automatically. It doesn't sound like a screech to me, just a whirring motor.

i didn't know that. the screeching and electric motor sound were different.

 

[AZMikeL]

Could be fuel pump as well. A lot of cars run it for a bit after shutdown to dissipate heat in the fuel lines. This prevents fuel from boiling in the lines and making it hard to start the next time. Not sure if the Bronco does that or not.

 

[Jimmiee]

Interesting. where is that pump located?

Under the rear of the truck.

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