I had an A4 in my Cal when I bought it and the guy I bought it form
told me to replace it because it didn't work. All I did was replace a
completely clogged fuel filter and it ran pretty well for a long time
after that. I bought my boat in Long Beach CA and sailed her to Florida
and then again around the Caribbean for another 4 years on the A4 and
only replaced it after being moored in an electrical nightmare for 6
years. The engine actually was so bad that I broke much of what was
left of it out and off with my hands. (even with zinks - not a good
thing)

I swore by the A4 because it was so quite and easy to fix. Long story
short, I repowered her with a 28 hp diesel 2 years ago. The total cost
with me doing all the labor was about 10K because there are many other
things involved like linkage, a new fuel tank, exhaust, exhaust lifter,
train, shaft, prop size and the list goes on. When I was all done with
it I started cleaning out all my old spares. I had 2 extra carburetors,
a new distributor, plugs, wires, and just about anything else you can
think of. (BTW, my impellors were the same size so now I have lots of
spares there). I now use less then =BD an hour as opposed to 1 gal an
hour with the A4. I have a huge amount of extra power that I never had
before and the engine is actually not that load.

There are pros and cons with both but some of the pros of an A4 are not
often talked about. In Mexico, Nicaragua, Costa Rica and Panama, I
needed fuel and GAS was the only thing around. Others with diesels
where stuck. Anywhere that there is a car or outboard motor, you will
find GAS but diesel is rare. The A4 is extremely quite compared to a
diesel and most important to me, if the A4 is running, why on earth
would you spend $10,000 or more and a month of your life changing it
out?

I put 20,000 miles on what was suppose to be a dead engine. My advice
to anyone with an A4 is that if it ain't broke, don't fix it.

************ A4's use the same electrical as one of the old Mercury
engines. I have it written down somewhere but all my books are in
storage and I have forgotten the details. If you have an A4, the price
of buying something like a distributor cap from an A4 company and
buying the same thing from mercury at discount auto is about ten times
the cost. I bought my distributor cap and rotor plug for my A4 for
about $6 from chief auto. The guy in the Miami store new all the info
and saved me a ton of money.

Before you buy anything for an A4, look up what I am saying and find
the numbers. You will save a fortune.