As the title says, all mercury stuff, but the port side moves faster than the starboard side. Is there a way to adjust the pressure on the pumps to make them trim out more evenly?

TIA

Mike

Check if both pumps have similar length battery cables, positive and ground. Good chance the slower pump has lower "operating" voltage from more voltage drop across the cables. Hose lengths and over-tightened/crushed flare seats, the small ones in particular, can raise operating pressures during trim too.
Pump maximum pressure can be adjusted internally, but that may not fix the issue because the pump doesn't usually reach maximum pressure until the cylinders reach full travel. There are different rate pumps (different height gear pumps), but if the pumps are original Bravo pumps, they should be the same and should be set to the same maximum pressure.

it could also be a tight cyl on the slow side. run all way up and clean shafts with really fine paper. 600 or 1000 grit. you might need one or two cylinders. rebuild is pretty easy if housing isn't too corroded up. could also swap pumps and see if slowness switches sides.

Put the battery switch in "Both" position and see if they trim closer to the same speed.

I generally run with the switch in both, so it's not that.

Could be a voltage issue but I can put a Volt meter on both and see if it drops. When I hit the switch. That would confirm or rule out the power cables

not necessarily. if trim cyls are tighter on one side, they will put heavier load on that pump and cause greater voltage drop. but start with the cheapest-easiest thing and clean all big wire terminals. ESPECIALLT both ends of the ground wire from trim pump to block. batt wire from block to neg terminal is prolly not an issue or it wouldn't crank motor. pump ground can also be straight to neg batt terminal.

i have seen that problem many times,the valving in the pump and the motor itself get weak with age,the fix is a new trim pump.doug russel sels them at a fair price,i have bought quite a few of them over the years.