Originally Posted by MBDiesel
Anyone have a tank lift pump whine in their 2015? It's not terribly loud outside but I can hear it inside. Pitch is voltage dependent; it drops a little when the electric PS pump is working hard and isn't as high with the engine off and ignition in run. It seems to be not as bad with a full tank and gradually gets louder as it empties. No performance problems that I can tell; it's just annoying to hear it in the cabin. As far as I can remember it did this since new. My '14 made noise but it was more of a quiet hiss than a definite whine.
Dealer didn't find any problem but the tank was full, they probably tried to listen in a noisy shop and I had a few other things on the work order.
Sometimes I can hear mine. Other times I can't. Frankly, I'm not really sure why I hear it sometimes and not others because I haven't been paying attention. When I hear it, I'll ponder it for a couple seconds and realize it's the lift pump, but I've never taken specific note of the conditions (fuel level, temperature, etc.).
If I had to guess, I'd say that these factors make it louder:
1. Low lubricity (cheap) diesel like you'd get at a truck stop. I've never noticed it while running B5 or Chevron Premium, but I can't always get that.
2. Higher mileage on the fuel filters. I've noticed it more as I put the miles on the filters. Approaching 15K miles, I notice it more than I did at 5K miles.
3. Lower temperatures. I hear it more in the morning than the afternoon.
It could be I'm making all this up. Memory is a funny thing. I'll starting paying more attention.