I have a 1969 220D as a project/ restore car that recently died on me. It was running well for quite a while and then began blowing white smoke and stalling randomly. I did regular maintenance overhaul, filters, oil, etc. just to make sure it was in good shape and then tried to prime the injectors. That's when I found I can only get fuel through the pump to injectors 3 and 4.

The question is, when one of these injection pumps is failing, is it possible for it to still be pushing fuel to some of the cylinders? Also, is there some way it can just be backflushed or cleaned if it's clogged or blocked? If I have the IP rebuilt, I will need some timing specs for removing and replacing the pump.

Thank you.