d8h fuel trouble

hello out there, I have 1969 d8h dozer . the issue with it is low fuel pressure.the tractor only had 20 to 22 psi at fuel throttle. I have changed the primary screen and filters,have removed and inspected fuel feed line from tank, its ok, fuel flows freely thru line and thru primary screen and steel line to the transfer pump.i have replaced the transfer pump with a brand new one, the new pump also came with a new fuel bypass valve. but no improvement in the fuel pressure.thought that mabee it could be the valve at the bottom of the hand primer so removed it and blocked it at the filter housing with a plate off of another cat that didn t have a primer. still the pressure is at 20 , my cat manual says it should be 32psi plus or minus 7 psi this dozer runs great except for this low power issue,all the cat service troubleshooting manuels say to start by making sure there is minimum of 25 psi. also I have unhooked the throttle linkage and pulled the governor lever by hand just to make sure its not a linkage problem. I'm stumped, any ideas would be greatly appreciated thanks

d8h fuel trouble