how much can you turn up the pump with out having to worry about getting the egts to high on a 91 f250 7.3?

I personally wouldn't go more than 20% if you don't have a pyro to watch. We have a 1989 7.3 no turbo that has had the pump turned up 20% for a long time and it does pull pretty good and gets 17-18 mpg on the highway. Hope this helps, good luck.

I always heard that to just turn the screw in a half turn or you have to adjust the timing if you go anymore. I would get a pyro before I done anything.

Half a turn is a LOT, I bet you meant half a flat... never heard much more than a flat (side of the hex) at a time adjustment, max I have ever heard was 2 flats...

When I had my pump rebuilt/ modified I told THE MAN it was for sled pulling only, I have the fuel screw maxed out and when running empty or playing around town the temps will stay in check but on the 4 lane I can peg the pyro and turn day into nite, Give it one full turn and don't flatfoot it for no more than a minute untill you get a pyro.