Charlie Brown wrote:
I'm considering a boat with a 90hp Johnson outboard.

Excellent choice!

How long has
this company been out of business?

70 years.

Johnson was no longer autonomous following its purchase by
OMC(Evinrude/Elto/Lockwood) in 1935.

A lot of used boats seem to have
Johnson/Evinrude motors.

A lot of new boats were sold with them. The V-4 85/90hp, after
1977/1978, was a de-tuned small bore version (92.6 CID)of the 115hp &
140hp. After about 1985/1986, the 99.6 CID 90 was roughly equivalent to
the earlier 115. (dates are approximate - from memory) The whole basic
design has roots back to the 1958 V-4 50hp.

The reason so many are still around is the ability to repair them with
mostly ordinary tools, the Mercs required a vast array of "special
tools" to perform otherwise ordinary service.

Are parts readily available?

Yes. OEM from the parent company, Bombardier Recreational Products,
(www.johnson.com) and good aftermarket sources.

Rob