Puts to rest the ideal that timing is not very critical on these engines. For running timing to be simular to drip timing I still feel the pressure in the base of the fuel pump might be important. From your post I think yours is probably good. Or even a little high.

Low pump feed pressure I think will retard actual running timing to some extent. Other problems might be generated as well. I only say might because not much is proven other than things seem to indicate this strongly.

On 616 engines especially I feel it is important to have this base pump pressure about correct or a little higher than recommended range at speed especially. The same for 617 engines although perhaps not quite so critical. In my mind it might be the source of the common number one rod bearing failure on far too many 616 engines.

This is unproven but based on much more fuel being fed to the number one cylinder than the other three when base pressure is non existant at speed for practical purposes.

Until proven otherwise I will not drive a 240d with low basic pump feed pressure. Again I am far from certain so just a precaution for a possible long shot . Too easy to rectify than to ignore. At worse your fuel milage should improve if corrected.

The 616 engine also seems too well engineered for this problem to be just mechanical design. Although other possibilities do exist.

The 617 has more power strokes somewhat mittigating the load on the number one rod bearing under low base pressure situations. The failure of the number one bearing is still there on 617s but at a much lesser frequency as a consequence of the additional power strokes per engine cycle I believe. This creates less stress on that number one bearing under simular overfuelling of the number one cylinder because of low injection pump base pressure.

Mercedes or bosh want this base pump pressure present at a reasonable rate. So much so they wanted it checked in these cars at dealerships when newer.

Anything from an obstructed tank screen, weak worn lift pump to plugged filters can and will lower the base pressure. I notice since this all started quite awhile ago our esteemed on site mechanic Hunter is rebuilding a whack of lift pumps now. I would like him to post his current views if possible.

It took me quite awhile to figure out how filter changes upped fuel milage. When I found the suspected reasons I then knew to change the filters just when the base injection pump pressure was starting to drop away.

Waiting for the fuel filters to give clear signs they need changing might damage engines. It is already common knowledge that fuel milage is comprimised by obstructed fuel filters. Comon logic stated it should be otherwise.

I can never see it as a problem to check your base fuel pump pressure before drip timing an engine. Especially if your fuel milage is generally lower than typical examples.