Pump Sound Inside - From the back - Fuel Pump?

[Awfiretto]

Ok TYF peeps, I need your help / experience to point me in the right direction, I have done my fair share of searching already, but hoping this post may help.

Noticed a pump sound (soft buzzing) coming from the rear 3rd row area inside the vehicle. 1st it was intermittent at the end of long trips, or randomly as long as far as I can remember. Now it's noticeable most of the time when idling. Maybe it's me listening for it more now...

I thought it might be AutoLevel... which is why I never paid much attention to it. However... it appears even though the truck is coded with the RPO - ZW7... the previous owner must have removed it all and then put in Monroe Reflex shocks. The pump is not there, and no lines to the shocks, and the shocks have a Reflex sticker on them. Disappointed about this, but live and learn.

Trucks got 115k on it, 2007 LT 4WD. It runs fantastic.

Questions:

1:Fuel pump right?

2: Normal or replace it? (has anyone lived with this sound for years? etc.)

3: (Doubtful) Is there any way legit way to test it?

4: Any other sounds/signs of a bad dying fuel pump?

Thanks in advance.

 

[PG01]

Park next to a wall, preferably in a garage with no radio or other sounds...turn key on engine off (koeo) with windows open, driver side only, and listen, you will hear it better.
It will not last long once its getting noisy and leave you stranded at the worst possible moment.

 

[kbuskill]

I was going to say auto ride compressor but you shot that down rather quickly.

You can check your fuel pressure with a mechanical gauge at the test port on the fuel rail to see if your pump is getting weak.

Or if you have access to a scanner like the Tech2 or even a Bluetooth OBD2 scanner you should be able to view the fuel pressure.

The Flexfuel trucks pump are supposed to put out about 43 psi.

The non Flexfuel trucks I believe are higher psi but not sure... maybe 55-60psi.

James @swathdiver could probably tell us more definitively.

 

[89Suburban]

Sure it's not the little interior fan temp sensor thingy in the roof? They make an annoying buzz sometimes.

 

[kbuskill]

Sure it's not the little interior fan temp sensor thingy in the roof? They make an annoying buzz sometimes.

That is the interior ambient air temperature sensor above the drivers seat.

My LTZ Burb has 1 in the rear headliner between the 2nd-3rd row as well.

 

[Lancem]

If it is the fuel pump I've had ones that were loud as hell and lasted for years, I my experience just never fill up over half, they always seem to go out when the tank is full

 

[Awfiretto]

Sure it's not the little interior fan temp sensor thingy in the roof? They make an annoying buzz sometimes.

Did some more listening tonight, and sure enough that little thing was buzzing!̇ thank you!

Was relieved to find it, sorry for all the fuss, but thanks

 

[Awfiretto]

That is the interior ambient air temperature sensor above the drivers seat.

My LTZ Burb has 1 in the rear headliner between the 2nd-3rd row as well.

I guess there’s one in the back of Tahoe too. That’s what it is!

 

[kbuskill]

I guess there’s one in the back of Tahoe too. That’s what it is!

You can replace them for about $20-$30 a piece OR I have heard of people blowing them out with compressed air.

I replaced both of mine and it got rid of an intermittent cooling problem I was having with the A/C.

 

[swathdiver]

I thought it might be AutoLevel... which is why I never paid much attention to it. However... it appears even though the truck is coded with the RPO - ZW7... the previous owner must have removed it all and then put in Monroe Reflex shocks.

ZW7 is Premium Smooth Ride Suspension, just standard shocks and springs.

ZW7 and G65 means that the rear shocks are self-leveling Nivomats.

There is no compressor associated with ZW7.

Z55 with G69 is what the LTZs, some SLTs and Denalis have and maybe the low end Cadillacs.

Z95 with G69 is Magneride. G69 is the RPO for the air compressor.