I was down at the Indy today having the transfer box output flange oil seal changed. They'd just taken a fuel pump off a 4.4 TDV8 where the owner had run the car on fumes a number of times, which causes the pump to seize due to lack of lubrication.

I asked them to show me the area where they wear, which causes the mild rattly noise.

Hopefully these pics illustrate the cause. If you look closely at the spigot in the centre of the first pic, you can see the top half is fatter than the lower half. in particular, the bottom right is where they wear over time.

A very common issue and not a failing pump.

Their comments are that if you can live with the noise the pump should be fine.

Click image to enlarge

Click image to enlarge