injector pump pajero

Sure there is not a problem elsewhere, blocked line or something ??

Pajero Forum search would reveal stuff on this. I have adjusted my pump because it was belching lots of black smoke. When its too lean it dies early & is sluggish
on pick up.
On the rear end of the pump is a round plug about 15mm dia. with a slot. Undo this with a screwdriver and inside the pump is a flat wheel with small teeth.
With a small screwdriver click the wheel anticlockwise say 10 notches and see if it makes a difference on the road without excess smoke. This may be the problem
and you should take note of the no. of clicks iun case its not.
If the pump has been replaced without setting the timing properly it wont go well, a setting a bit in advance of factory seemed best on mine.
Anyway your mechanic should have done ALL this, but they even seem to come from the factory with less than optimal settings. Get it all right & it should go
well with good ecenomy too.
If U want to see what U R doing before resetting it take off the top diaphragm cover & look underneath to see the wheel U may adjust but done lose any bits.

I would take it back to whoever did the work and tell them to get it right, the instant you touch it he isn't responsible.