Serial number gone on Force 90hp

[Cwagon1971]

Trying to find the year of my Force 90hp. Serial number is wore off or hidden. Any ideas?

 

[Jiggz]

Force 90 ranges from the year 1990-1999. Ignition system groups these motors into 4 categories, i.e.1991, 1992, 1992-1995 and 1996-1999. Mechanical system is divided into three groups. For example the LU gear ratio is initially grouped into two, 1.93:1 ratio ( 1990-1994) and 2.07:1 ratio (1995-1999). But those with 1:93-1 ratio are also divided into two groups, i.e.1990-1992 (with gear oil capacity of 26 oz) and 1992-1994 (with gear oil capacity of 35 oz).

To find the gear ration mark the prop and count the number of rotations on the flywheel it will take to make one complete prop revolution. Rotate the flywheel only in the clockwise direction (looking down on the flywheel). And if you know the amount of gear oil to top off your LU, then you can guesstimate the year of your motor within about a year or two.

When you have enough post you can also post pic of the ignition system and the LU and a 3/4 view of the motor uncovered. Most forum members can readily tell models and year with good reference pics.

 

[jerryjerry05]

If the boat/motor combo is original??
​Then send the hull ID# to the boat manufacturer and they can tell you the model and any other info you need.

Also on the top cyl. under the electronics should be a foundry stamp.
The center of the stamp should be the year.

The model# was assigned when they made changes to the design.
Sometimes the mod# change was just a hose clamp change or something simple.

Look on the starter it "might" be original and have the year on it???

 

[estes82]

I have the same problem with my 1999 75hp. I have been told to find the welch plug and the model number should be embossed inside of that. However I have not found my welch plug because I think mine involves removing the lower cowl. I just have not done that yet, and I know mine is a 1999 because it has an emissions tag on it. Your welch plug could be in a different place than mine too by the way..? Some of the more seasoned "wrench-turners" here might want to weigh in on this topic?... Hope this information helps as this is just what I have been told.

 

[Jiggz]

A welch plug on this engine is a part on the carburetors. Never heard about engine model being stamped on them. I doubt the engine model will be there. Unless you are referring to welch plugs on auto engine blocks or so called freeze plugs. However, none exists on this Force engines that I am aware of.

 

[jerryjerry05]

The welch plug is about 1in diameter. It's silver with a number stamped in it.
Usually starting something like OE203000 all have the 8 letters and numbers.
​You can pretty well bet if it's a Mercury equipped motor it has a plug somewhere.
If it's a 95-99 look!!
My neighbor has a 98 75hp Mercury and it took me 4 tries to find the plug.
It was on the stbd. side all the way on the bottom under a mess of wires and hoses.

​Gonna call my friends at Mercury and ask if there is a freeze/welch plug.