Jay, if you want to load test your battery, yank it out of the boat and
take it to an auto parts supply store that handles batteries. The store
is sure to have a real battery load tester, and you can get a reasonably
precise answer to the question of "battery health."

I am afraid that the salesman will tend to bad mouth the batteries in
order to sell their new batteries. And the batteries are inside a
console where I have a hard time moving them out and moving them back.
I think I will check them in place instead of bring them to the store.
Hopefully people whose batteries are in more accessible place will take
your advice.

I don't know what Merc you have, but I have had several, and once I
hooked up the muffs and turned on the water(you don't need or want full
pressure from the average household water system), I'd start up the
moter and in a few seconds water would come out the pee hole. If water
isn't coming out that hole in short order, you probably have a shot
impeller or a clog somewhere in the system. To the best of my
knowledged, water is not going to come out the pee hole under the
powerhead unless the engine is running and the impeller is pumping water
up to the powerhead. The newer, larger Mercs have a way to pump water
into the powerhead without using muffs.

Thanks for telling me that I must start the engine in order to test the
water pump. Now, I can concentrate my effort in getting water into the
motor.

For some reason, I just don't have much luck with the flushing earmuff
adapters. I can see one of the reason why I have a problem is that
area where the water intake holes are have an slightly depressed area
facing the forward area. I guess that depressed area is for helping
water to enter the water intake holes. Unfortunately, when I place a
flushing earmuff adapter over the water intake holes, water tends to
come out from that depressed area. I believe this reduces the water
flow entering into the water intake holes. Next spring, I will play
around with different water pressure level, different mounting
positions...etc.

Jay Chan