I went through this Firestone two years ago, and barrel tested
it, but it never seen the boat. I "presumed" it was ready to
do a quick barrel test, then venture on the lake, NOT, lol.
It started right up, but would not "wind up" to speed.
Played with the carb settings as I though it was loading up.
Turns out it was only firing on one cylinder. While doing
a "air gap" spark jump test, I noticed the one plug cap
arcing inside the cap. They were some funky, old, motorcycle
style caps, that are now in the garbage!
Anyway, it runs okay now, but it was only pumping water
at higher speeds. Pulled the lower unit apart, expecting
to see a new impeller "ate up", I find what I believe is
an old impeller, with vanes not even touching the liner
on one side 😮
I put all new needle bearings and seals in the LU, so would
have presume I found a new impeller.
I have feelers out for a new one, but was wondering if anyone
ever found a modern replacement?
It was two opposing slots in hub that goes over the 1/16" pin
in the drive shaft. The specs…..

Water Pump Impeller, Part #493-5100
Impeller cup ID = 1-1/2" x 7/16" deep
Drive shaft OD = .500

Also, it has the funky sliding collar that locks the motor
from tipping up while running in reverse. Only thing
weird, that while in "neutral", the collar is still locking
the lower unit. Forward and Reverse seem to be
equi-distance from Neutral when shifting into the different
positions. Found another Firestone with the same set-up
and it too locks in Neutral.
Is this normal, and if so, why? lol.
Thanks for your sage advice!

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