We used to have a GT150 w/ a Merc 115 and it would run about 42 mph wide
open (if I remember right). My guess is yours runs about 38 mph wide open
if that much. Given that - at 9 gallons per hour that would equate to a
little over 4 miles to the gallon. I really doubt it will get that at wide
open. Probably 2 miles per gallon if your lucky. Now it should get 4 or
better at about 3/4 throttle or less.

New engines do get better fuel economy. A new 90 (they don't make 85's any
more) will also have a lot more power as it is rated at the prop and yours
is rated at the powerhead.

If you really want some fun (I think that boat is rated for a 135) get a
1990's Evinrude 120 V4. That will wake it up.

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com


"Guy Shepherd" wrote in message
om...
My brother has just bought a Glastron GT150 with a Johnson 85hp V4 (2
stroke) outboard (circa 1975-1978) and whilst he is very pleased with
the combination, the fuel consumption seems a little startling.

Anyone have any idea what the approximate fuel consumption ought to be
on this engine at full throttle? I guess it would be better at more
moderate throttle settings, but where's the fun in that!?

Are the modern equivalents of this engine much better in terms of fuel
consumption?

Cheers

Guy