Does the XUD injection pump stop injecting fuel when engine braking down hill?

[kenbw2]

I've heard that "modern" engines cut off fuel supply when going downhill

I recently tested my idle fuel consumption to find that it was 0.8L per hour! I'd love for that to not be true when I'm rolling down hill

Is the XUD9 Bsch injection pump clever enough to detect engine braking and reduce fuel supply accordingly?

[Paul-R]

I don't think so. On those engines it uses less fuel to coast down hills rather than leave it in gear on the overrun as it's simply turning over at a lower (tickover) engine speed.