I never done a 4 pot, but the 5 pot Pre-PD engines had adjustment on the pump belt idler/tensioner.I'd guess that the timing belt pulleys were 'dabbed' rather than the correct locking tools used. Very few bother locking the HP fuel pump, even less bother checking it after the initial two rotations of the crank.
Some places don't even bother with replacing the idler pulleys or tensioner and just do a 'slide-off, slide on' with the belts.
It's been quite some time since I done one, so the specifics are a bit vague, but IIRC the belt was done using marks on the cam/pump/belt, then you had to do the final adjustment using a computer to monitor pump timing as you adjusted the idler/tensioner to get the pump timing within spec.







