im having a issue with the power steering. its a twin pump fully hydraulic set it. everything is working currently but i have both returns after the coolers going into 1 reservoir, there seems to be an excess of flow going to the reservoir and it looks like a water fountain in there and it is causing it to leak out the vented fill cap. i have fallowed and triple checked the diagrams sent from imco and hardin, they are imco rams, latham reservoir, saginaw pumps that i removed the original reservoirs and installed the tanks for remote reservoirs.. before i switched to a single reservoir i had stock saginaw pumps on it and if i started 1 engine it would make the other pump overflow out of the cap, i have the imco priority valve, im not sure on the helm itself i cant find any numbers on it that mean anything. it is a 86 chris cat with supercharged ls3's been a project for a couple years now, finally down to the small stuff, any help is appreciated.

From what you said " it looks like a water fountain in there " the issue is more than likely the return lines to the reservoir. You are pumping two pumps and that flow has to go somewhere. How large is your single tank? There are two things to try.

Make the retune line enter the reservoir horizonally not up though the bottom. Supply to the pumps as low as possible in the tank. All fluid will run though the tank.

The other way is to put a Y fitting in the return lines from system then into a 90 degree tye end into the tank " bottom or side " Run the pumps supply lines off the tye that is connected to the tank. This way you are not running all the fluid through the tank and using it as a true reservoir. You should not see much fluid movement in the tank this way.

You can't beat basic physics. If there is X volume for fluid in the system:

Hydro cylinders
Reservoir tanks
All the hoses
Pumps

A single cylinder steering system will have res volume change...as the cylinder rod displaces fluid...as the rod strokes. Twin rods moving opposite..likely have minumal res changes..the fluid volume equalizes.

Unless you are aerating the fluid or..as mentioned above..the return lines are causing the reserve fluid to spray out?

it is your typical latham reservoir maybe 2qt but only fill half way. i cant put lines in horizontally because it is the round plexiglass/ lexan it has ports on the bottom for return lines, i can try to tee in the feed line to the pump as that is about 2x the size hose so it would reduce pressure in the rez, so i will try that thank you

fluid is not aerating. its more or less the engine that is not being used because of the priority valve is returning fluid so fast, if only one engine is running i see very little movement in the reservoir.

the return lines come straight into the bottom of the reservoir its a -6 (3/8) hose and there is enough pressure out of the hose that it sprays up through the 3-4 inches of fluid and it hits the top lid of the reservoir. the lid has a plug in it with a slot on the threads for a vent. after 10min or more the bilge in the boat has power steering fluid all over the place.

Oh great I just did this , also had 2 resevoirs and could not figure out why if I ran one engine the other would overflow.
I went back to a single PS pump till I could either tie them together parallel or just use one. I thought that would be the fix.

never really understood the twin pump thing. in all these years I have only ever seen maybe one failed pump. as for "I want to run either engine and still have power". well I have run plenty with out power and it is not like it is impossible plus you are not on plane running 60+ mph with only one engine so just go for simplicity and deal with turning the wheel if you dont have power at the moment. every twin pump setup I have dealt with has been a pain and has more issues than they are worth.

Hi 86 chriscat, this is a link to a Teague on Tech on twin pump application. Teague On Tech: Q & A with Bob Teague April 2020 | Teague Custom Marine https://share.google/p5VkzcWwJPNp1wzEU
I run the dual pump/single reservoir with zero problems or leaks. Double check how plumbing of the priority valve is routed. If the system is pressurizing the reservoir its possible priority valve is worn or broke internally.

Some are easier to turn than others. In my cat , I`ve almost hit a dock a few times because you need the HULK to turn the wheel and I`m pretty strong if I do say so myself lol. add some wind to that and forget it. My other boats were not as hard without PS.