Fuel Pump Whine - 1998-2000 V70XC Models
For some reason the 98-00 V70XC fuel pumps tend to whine in a very noticeable way.
To tell for sure if it is the fuel pump, start the vehicle and sit at idle with all the windows up in a quiet area. Lift up on all four window switches at the same time for 1 second then release.You will notice the pitch of the sound changes slightly due to the momentary increase in electrical load. The increase in load decreases the system voltage causing the pump to slow momentarily which changes the pitch of the pump. If you have run into this and you’ve been told ‘you’ll have to live with it’ you can have peace and quiet!
The pump noise seems to resonate from the U shaped tunnel under the (second row) rear seats.The way to eliminate or at least reduce the noise is to follow the bulletin that was circulated through the dealers around the time these cars were new.
Remove the bottom rear seat cushions and pull forward the carpet.Note the U shaped structure that supports the seat bottom cushions and located the holes throughout this channel.These holes must be filled with a foam rubber or similar material to help lessen the resonance through this area.Another step that can be taken is to apply Dynamat or similar material to the top and front of the seat support structure to reduce the amount of vibration that may contribute to the noise. Be sure to use a good amount of material to fill the cavity in the seat structure and then reassemble the seat cushions. Following this method, you should notice the noise is greatly reduced.