Oh mighty OSO, I need Thy help. I have a 2001 Formula 312 Fastech with stock 6.2 Mercruisers and standard (non-external) power steering. There is one power steering pump on each engine and both have full fluid and are driven by each engine's serpentine belt. I noticed that the steering wheel turns easily with either both engines running or the starboard engine running, however, the steering wheel is very hard to turn with only the port engine running. I don't know why I haven't noticed this before. I've heard that it maybe intentional that only one engine's pump is plumbed into the power steering system. Or are both pumps supposed to power the steering independently? I am wondering if I have a faulty, port-engine power steering pump or did the factory only design the system to run off the starboard engine pump?

No you are set up to run off one pump. The other is just along for the ride. There is a valve that can connect everything up with 2 pumps, but it is cumbersome and involves more hoses, etc. that can fail so most manufacturers just leave the pump on the motor and plumb the pressure to the return. At least you have a spare pump in the boat when the first one fails

Thanks Insptech!

I am having a simular problem.
I have both pumps with check valves plumbed into one large return tank ,the starbard motor works fine when running the pump but when just on the port motor I have no steering at idle seems ok when I am at 2000 rpm on the port motor ,any ideas what is going on,I learned this when the starter took a dump on the starbard motor and had to idle in on the port motor

HELP !!!! Thanks Wayne