Mercury 4cyl 80hp Outboard issues

Will Liston

Cadet
Joined
Jul 9, 2013
Messages
19
Hey folks,
This is my first time actually posting on this forum even though I've been creeping around for a few weeks. It's like a treasure trove of info and parts...

I'm restoring a 1969 Glastron Swinger v-176 Tri-Hull with a 1980 Mercury 80hp 4cyl outboard SN#5583641. Long story short is I've taken in out four times and have been towed in 3 of those times.

It feels like something is holding my motor back... so much to the point that when the boat is pointed into the current the engine bogs down and stalls out. After it stalls it is flooded until I tilt it or let it dry out. It also stalls out and dies at around 1/4-1/2 throttle.

Here is what I changed so far --
Impeller
4x Sierra Ignition coils
4x NGK Spark Plugs
Lower Unit Lub
Marine Grade Battery
Fresh Gas and Seafoam

Pulled apart and cleaned Carbs. Floats look fine.

I thought the issue lied in the ignition coils. Which definitely seemed to help some... Compression in all 4 cylinders is within 10% of each other.

Does anyone have any ideas:facepalm:. The engine has two carbs. It seems like there is way to much gas in the cylinders. It looks like there is only one needle valve on each carb.

Thanks
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,420
Re: Mercury 4cyl 80hp Outboard issues

Maybe the fuel pump diaghram is leaking raw fuel into the crankcase? The rebuild kit is cheap and easy to install. Leaking diaghram in fuel pump would cause hesitation or stall, plus potential lousy idle quality.

Other kinds of leaking diaghrams cause parenthood.....
 
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