Mechanical diesel pump tuning

I have a 1997 toyota hiace with the 2L diesel none turbo, no ecu engine. (just how i like them). Does anybody know if the diesel pump can be tuned easily to give a bit more fuel and power?, Something like the old transit engines with a bosh mechanical diesel pump, you could simply turn an allen key screw to increase fuel flow, small increments of course to avoid blowing it up! Its the same engine in the early hilux and the land cruiser i think. Thanks.