Quote:
|
regulator is there in case of over pressure
|
A fuel pressure regulator is needed with a positive displacement pump because they don't make pressure without restriction; only flow.
EFI injectors are designed to work best within a given range - and there's a minimum. 3 bar (45 PSI) is the typical spec, which ensures good fuel atomization. More pressure simply delivers more fuel for the same pulse width (a fact often leveraged with forced induction/rising-rate pressure regulators) - but unlikely that pressure being too high would kill the motor - and there'd be obvious signs of it being stinking rich. Low pressure would tend to make fuel dribble out of the pintle rather than delivering a fine mist. and there wouldn't be enough of it.
Sounds possible that either the pump or regulator may not be keeping up with specs at higher RPM. And injectors can get partially clogged with junk.