What year is my mercury 40 hp (402)please the number is 9034091

Product Line Year H.P. Model Number Model Description MERCURY 1978 115 1115628 MERC 115

If the serial number is 3065967, it is a 1971.
(Not 80659677??)
It appears that the last year produced was 1976 with serial numbers starting with 4314385.
8 and 3 misreading is not uncommon.

Only things I could find ...

1. S/N beginning with 8075603 , 2.2 Hp was 1984
2. There was a different reference that different countries could have different serial number series which complicates matters.
3. But there was also a reference indicating for outboard motors ... that the nameplate which has the model and serial number ALSO had the year written down ... the last 2 digits of the year in a box in the lower right hand corner

1995 I believe. Here is a link to a chart - omit the leading "0".
MERCURY OUTBOARD MODEL YEAR GUIDE 40 HP 4 CYL 50 HP Mastertech Marine

1984 is the year

the serial number begins 2487558 and continues past 2491265 and as the beginning serial number denotes the year , your engine is 1969 model
it shows as a 2 stroke with auto oil injection
check the heads
if the plugs are in the flat of the head and there are no rocker covers it is 2 stroke
talk with a mercury /mariner service center

Try this site. http://boatinfo.no/lib/mercury/manuals/mercury_1965-1989_2-40.html#/0
Good luck......

OD numbers range from 86 to 93.
The year is determined by the stripe colour on your cowling.
Good luck..........

According to this list (link below) serial # 3114119 falls into the 1971 production range.
MERCURY OUTBOARD MODEL YEAR GUIDE 115 HP 150 HP Mastertech Marine

Quiksilver marine dealers !