1989 Mercury 40hp wont accelerate in gear UPDATE

Joined
Jul 17, 2006
Messages
73
I have been pulling my hair out with this thing. 1989 40hp 4cylinder 2 stroke.

First off, when putting a timing light on #1 cylinder, the timing marks are no where near close at cranking speed. Moving the spark advance lever does nothing. When timing marks are in the "window" the piston is probably only a quarter away from BDC and on its way back to the top. Is this normal?

It has a new trigger on it as I initially thought that was the problem.

Went through both carbs, was not getting fuel to pull through the top carb as well as the bottom, a new set of reeds took care of that. Now fuel flows evenly through both carbs.

When running the motor sounds slightly labored, then when put in gear to accelerate, it falls flat on its face and dies.

Compression is 125-130 across all 4 cylinders, bright blue spark on all four also. After running for a bit, the #3 aprk plug is hot while 1,2 & 4 is only lukewarm.

Any thoughts guys? Is it something simple I am overlooking???

Thank you!!!
 
Joined
Jul 17, 2006
Messages
73
Ok,

So I mentioned I changed the stator. The replacement stator I used was removed from a recoil start engine, same size, same year. Part numbers are slightly different. Other than maybe not charging the battery, what would the difference be between the two? Would the electric start flywheel be compatible with the recoil start stator?

The timing appears to be nearly 30? off at cranking speed. Would taking the ten bolts out of the electric flywheel and indexing in an attempt to get the timing correct work?
 
Joined
Jul 17, 2006
Messages
73
It is amazing how bad an improperly working (brand new) trigger assembly will make you pull your hair out. Motor is fixed.
 

Canufixit2

Petty Officer 3rd Class
Joined
May 20, 2016
Messages
99
Glad you found it ! Sometimes it takes persistence. Sorry you got no responses - but I wanted to thank YOU for posting the followup! Often times posters will have interesting issues - but then disappear. It's good for all of us to be able to know the end results even if you just got pissed and beat the crap out of te engine before you tossed it.
 
Joined
Jul 17, 2006
Messages
73
60'sboater The trigger is a CDI brand.

Canufixit2 I am kind of stubborn, and persistent. I don't like to get beat by these things. Thanks!
 

quicktach

Petty Officer 1st Class
Joined
Aug 24, 2012
Messages
394
Can you tell us a bit about what was wrong with the trigger assembly?
 
Joined
Jul 17, 2006
Messages
73
The new trigger I put on essentially made the motor way out of proper timing. The motor ran, just not correctly. My assumption was the trigger would be good, so that was the last thing I would have thought of checking. Wish I would have checked it three weeks ago now. Hind sight is always 20/20 though :)

Crappy part is that its an electronic part and probably no way for me to return it. $70 item.
 
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