From what I have seen, Denso seemingly has a design defect on the suction control valves of their first generation supply pumps. This has caused a lot of problems for engine manufacturers which use the same system.

I assume that it is for this reason that Denso has come up with a redesigned supply pump with an improved suction control valve.

I believe that local car distributors, with the aid of government should compel Denso to replace these problematic pumps with their upgraded pumps free of charge, and whether the vehicle is in or out of warranty. This is how consumer protection works in other countries.