Merc39

I want to run some evinrude engine tuner thru this 3.9hp
just because it's probably never been done before. With the
engine running can I remove the engine cowl without
jacking things up?

Start engine.-----Let it warm up.-----Stop engine.----Remove cowling.----Restart engine with hands around flywheel.

bigjohnson said:

I want to run some evinrude engine tuner thru this 3.9hp
just because it's probably never been done before. With the
engine running can I remove the engine cowl without
jacking things up?

Click to expand...

Removing the cowling while the engine is running particularly on this model is not recommended since there is a special technique to do it without the flywheel grinding away at the internals of the cowl. I recommend a 1/4" diameter braided cord with a double square knot of the end and place it in one of the castles and wrap one wrap around the castles and make sure your knot is held in place with the wrap then once more around, then give her a clockwise smooth steady pull. These engines start very easily once they're set up correctly. I now have 5 of those little one lungers and they are fun to tinker with. I've never seen an engine that will idle so slow. Other things to consider is a new waterpump impeller if its been sitting for more than 4 years and gearoil change. The impellers on these are notorious for the vanes breaking off after they sit for a while.

Yes I was thinking I will take a rope with me if I can't start
it by hand. Mine idles way low as well and runs like a top.
Already changed the impeller and gear lube.
This one is a 1967 and runs like new that's why I want to
clean it with tuner so I can get another 50 plus years out of it.