Persistent, constant, high-pitched tone

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I’m just looking to pick some brains and see if someone more knowledgeable than me can provide some direction.

I’ve got this high pitched tone, it’s like (beeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeep) but constant, there’s no start and stop. It’s almost like an audio whine if you have power wires too close with speaker wires. Sometimes it borders on a buzzing, but it’s always closer to the beep. It’s unchanging and independent of engine speed or load.

At first I thought it was an audio issue, but it’s most audible under the car and with all the doors and windows closed, though it’s also very noticeable inside the car. I settled on a fuel pump since it’s so loud under the car, changed the pump with a brand new oem ac delco pump. Still there... though at 14 years old and 150k it probably could use the pump anyway. I’m going to change the fuel filter today.

It happens at key on and goes for about 2-3 seconds, then stops forever until I start the car.. then it’s constant. That’s the main reason I went with fuel pump.

So now I’m trying to figure out what’s happening. I only had 1 DTC that I cleared and never came back... P1811, max adapt long shift. Can the noise be the tranny fluid pump?

I haven’t had a chance to check the fluid level, I’m planning to change the fluid and filter today since it’s been a few years.
 
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It can’t be, it’s ear-piercing... I know the pump whines at key-on and while running but thats more like a hum.

Even my girlfriend who knows nothing about cars was like, what is that horrible noise... after riding in this car for 10 years.

Unless the fuel filter is blocked up somehow and the pump is straining way harder than it should... in which case I’m changing that filter today so I’ll find out.
 
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See if there is a fuse for the fuel pump, pull it and see if the sound goes away. If it does
wink.gif
. If it goes away, i'd change the fuel filter first and see if there is any change, then the fuel pump.
 
Whack the bottom of the tank with a 2x4 and try throwing some 2-stroke oil in.

It might be some other gadget related to the fuel system like a regulator or some EVAP thing.
 
Try the filter, I always replace the filter when I install a new pump. I believe that is a requirement for the pump warranty.
 
1.. fuel filter. Most auto fuel pumps have brushes. the pumped gas flows over the pump motor to cool it and lube it. So 100% of the brush wear, copper and bearing wear end up in the filter. Always change it.

2. Check to see if some of the isolator rubber for the tank mounting and things around it have deteriorated. I suspect that some noise isolation rubber is gone somewhere.

Rod
 
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Sorry, it’s a 2004 Grand Prix GTP. I’m used to posting on a forum where my car is in a signature.. I don’t have that set up here.

Anyways, I did the fuel filter and it’s 200% better. Not only is the noise gone, but it’s dead silent... not even a quiet whine or hum. Better than before the problem started!

Thanks everyone for your input!
 
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