250SS shutting down when trimming

[doug@5rivers]

I have a 2021 250SS on an Excel Storm Cat 230. This boat is a tank! Over 3000 pound hull. When I switched to lithium batteries (3 replacing 5 lead acid) I lost nearly 400 pounds of batteries and chargers. Immediately after, my engine started shutting down on high temp if I tried to go to full throttle and trim it up. My engine is on an Atlas hydraulic plate and both are in the top holes, as low as they will go. I've checked everything except pulling the tubing to the water pressure gauge. I've ran 4 different props with same result. My props were a PowerTech 4 blade with the racing looking blades, lots of cup, 21 pitch. A Suzuki 4 blade 23 pitch. A Suzuki 3 blade 23 pitch. And now a Solix 3blade 21 pitch with almost no cup. I feel the boat is lifting too high when trimmed. Even if I'm trimmed less than 1/4 on gauge, if I hit a wake, it shuts down. When it shuts down it doesn't shut off, it drops back to idle. My water pressure gauge never reads above 10 psi and is very slow to return to that when I come off plane. Watching the water pressure gauge, it will go to 10psi as I take off and stay there as long as I don't touch the trim, even at full throttle (4800 rpms). As I trim up and my rpms come up, my pressure drops to nothing. Shortly after, if I don't trim down, it will shut down. The High Temp alarm is the only alarm and it will reset as soon as I turn the key off then back on. I've NEVER seen less than a full stream from the pisser. Water pump impellor and housing were replaced since this started. I run my Atlas plate as low as it will go.
This condition never happened before the lithium change-over. I could trim to 3/4 and run 6000 rpms all day. I never experienced this before. I'm open to suggestions. I hesitate to run my livewell full all the time or put ballast onboard. I'm contemplating going to a 6-8" set back jack plate so I can lower it.
Ideas or comments?

[Moonlighter]

It sounds like removing the weight of the lead acid batteries has resulted in the hull running higher in the water, and of course, the faster you go, the higher the hull rises.….

With the result that the water pickups are out of the water when the engine is running higher rpm and is trimmed out. All the data you have reported is telling that story.

You might be surprised just how much higher the hull is running without 400lbs of battery weight!! That’s fully the weight of 2 people. Thats a big change.

I think you will need to lower the engine height until you can maintain water pressure at those higher speeds and trim settings. How you achieve that is the question for you to answer.

[doug@5rivers]

I have a follow up to my previous post. I was at my wits end with this issue so I spent an afternoon going thru every YouTube video on Suzuki 250SS and engine overheating. I finally found a short video from a guide in Florida I think. He had a 250SS on a tunnel hull bay boat that was overheating. He took the water inlet screens off both sides of the lower unit and took a dremel and smoothed down the inlet side to the water inlets. He cut the inlets into the screens where there was smooth water flow. I thought what the heck! What damage can it do. A new set is less than $40 at Brown's Point. I took my dremel and did the same thing. Nothing else. I ran my engine this past weekend at Grenada Lake, MS in a tournament. My water pressure jumped to 10 psi and stayed there. There was a slight drop to maybe 8 psi when I trimmed my engine to 3/4 on the trim gauge. Boat wakes and rough water...no drop in pressure. I'm considering this problem fixed and all it took was a few minutes with the dremel.