Dont really know why.

Mine tend to get noisy on say a 3-4 hour drive, but although the weather is warm for here, fuel temperatures arent exactly anything to worry about. Rarely over 30degC when on the move.

So I dont see how it can be fuel temperature that causes it. But the pumps do sound like they are cavitating or something. Although in my setup, the fuel supply from tank to pumps isnt anywhere near what it should be. But as stated, even on very warm days when sitting queuing to race etc, fuel temps are higher as are ambient. Despite any noise my pumps make, it never affects performance.

I have seen a post on a US forum where there are some forged 044's about. Instead of the lettering being stamped in, it's more like engraved in to the body.

For the people above, they'd need to check fuel pressure and power supply to the pumps before saying any pump is bad though.

Ive been using my pair for a few years now with no problems