I bought a 20ft Bayliner Trophy with a 1998 Mercury 150 XL from my wife's
grandparents three months before her grandpa died, taking ashes out in the
ocean soon sad to say. I've done many repairs from scrapping the barnacles
off to reconnecting every thing electrical. The battery connections were
done with a vise, yikes! I recently built a 6' ski pylon hoping to have a
dual purpose boat with a huge wake to kneeboard and wakeboard on.

The boat ran great at sea level on the northcoast of CA but when I took it
to Trinity Lake with an alt of about 2500 ft is balked terrible on take off
without pulling a skier. It was hard starting (thought it was standard for
Merc's) so I messed with the throttle cable opening it up about a 1/4 inch
which helped both the starting and the take off but it was idling too fast
so I backed it off a bit. I didn't have a timing light out camping but I bet
if I advanced the timing a bit it would compensate for the altitude. I want
to run the boat both at sea level and up at the lake when the ocean is blown
out. I have a good manual but it doesn't give this type of tuning advice.

Any guru's out there for this engine?

Mick