Ok, so I have been tuning a little and playing with props. I am pretty pleased. Getting up over 70mph now but.........what is happening?

While running wide open when it approaches 70 mph I lose control of the boat. Especially in chop! The steering will practically freeze. Sometimes not turning left, sometimes not turning at all.

Then it takes about 5 mins of idling and pulling on the wheel and it comes back. do I need hydraulic steering or is my PS pump quitting on me? Fluid is full. Air in it maybe?

Like no steering at all or no power assist?

just a guess but now that you have more revs, are you over speeding the pump and hydraulically stalling the pump by cavitating the vane ? try backing off to revs where it used to work an see if it still happens if not just change the pulley ratio a bit and slow it down. don't forget that those pumps weren't ever meant to turn a lot of revs

FRIG THAT!!! Don't mess around with this at all. Get a pro to look at this problem before you head back out. Running that hard and suddenly loosing control could be very bad...don't risk it....get it fixed and fast!!!

my guess would be the actuator at the transom...assuming not hyd steering....

Like I can not even turn the wheel! not hard to turn...I mean won't turn!

i am honestly only about 500 more rpm than when I started with this boat. It was running @ 4600 when I got it, some bolt ons and new props and I am at 5000-5100 with trim.

aerating the fluid, mine has a leak i cant seem to find and i can tell you no assist at 70 feels like the wheel is locked, try flushing the fluid and putting synthetic trans fluid in

understood... was just a thought and an easy test. i am always leery of things that work fine one minute then something unrelated changes and then it doesn't work anymore. the " law of unintended consequences" at work...

i would still go out to a safe area and see if its a rev defined problem... i can't see how it can be an actuator... it would have to be the shuttle exposing both ports to lock it solid...

and actually , lil red is correct... it feels locked but actually all the assist is gone...

I busted a line on mine a few weeks ago - had to cut the line and drive back with no assist. It wasn't too bad at cruising and lower speeds, but I definitely had to fight it wanting to pull in one direction when it was under load. It really wasn't that hard to steer at idle or low speeds, however. Based on the fact that you said it remains "locked" even when you come back down to idle, it is starting to sound like you may have an issue with the helm, steering cable, or steering actuator. You might try disconnecting the steering cable from the actuator the next time it happens to see if it frees up. If it is still stiff, you have just isolated your problem to the helm or steering cable.

That is an old boat - if it is the original cable and helm, you might want to consider replacing it, especially now that you are seeing speeds over 70.