There is a super annoying mosquito like tone coming from my trunk, I’ll try to get it on video. It sounds like it’s coming from the fuel tank? Either that or the speakers but it really sounds like it’s from the tank. What is this coming from?

 

Does the sound stop when you open the fuel cap? That might mean you have a gas vapor leak that whistles as it goes past a seal.

 

Its definitely coming from the gas tank where the wiring harness hooks up. It doesn’t sound like a leak it sounds electronic. Is there a fan inside of it or something? Working on getting a video

 

Here is the sound it actually comes up good on video

 

Sounds like a fuel pump to me. Has the 12v mod been done to this car (bypass the fuel pump ecu), if so was it done such that the fuel pump runs at all times the key is on?

 

Yea I did some more digging and its gotta be the fuel pump. Not sure what the 12v mod is. ECU is possibly failing though could that interfere with the fuel pump?

 

There is a fuel pump ecu located in the panel under the drivers rear quarter window. It sends a variable voltage (really just 2 different voltages) to the fuel pump based on need which is sent by the engine ecu. Most people bypass it when it fails, common failure. There are many posts on here you can refer to on how to, etc. The reason I asked was if it had been bypassed and was made to just turn on and stay on with the key you could have someone turn the key on and off and listen to the sound and if it cycled then it is most likely the fuel pump.

 

Sounds about right the guy I bought it from said it had an idling issue and he fixed it, I wonder if this 12v mod was the fix? The sound turns off with the key out and back on when its in. So is the fuel pump wearing out and need replacing or is it common to be making this whine when its running full power? I'm thinking about ordering some sound deadening mats or some foam to put behind the back seats and the gas tank see if that brings down the noise a bit. The exhaust I have in the mail will also help drown out the sound.

 

If it is loud enough that you are hearing it from the drivers seat and you are considering sound deadening then yes I would be concerned it is on it's last leg. A fuel pump change isn't a huge job, but if you diy the job order the new mesh screen and new hoses since they are most likely 25 years old. If you order the screen, make sure you order it for the correct year, they changed early on.