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Magneto/Timing Adjustment on Mariner 40HP Please help! Bogging High RPM'S

P

PatrickMonahan

Member
I have a 40HP Mariner 6E9 engine and it runs very well up until high RPM'S at WOT and bogs down, I observe that when I put it into gear it moves a bit, the linkage to shoves the magneto linkage moves up a small bit( fully advanced in youtube video below) and it does not continue to move as the accelerator or throttle is increased to WOT. IN the video I have included it shows the boat at full throttle with the engine off, what I was wondering was if it( timing/magneto linkage) did not advance enough at high RPM'S could this cause it to struggle and stutter at high revs. Could do with a few opinions thanks. Basically I think its not in sync. Compression is 110PSI on both cylinders and spark is bright Thanks

https://www.youtube.com/watch?v=DotYg2cSEbI
 
PatrickMonahan said:
I have a 40HP Mariner 6E9 engine and it runs very well up until high RPM'S at WOT and bogs down, I observe that when I put it into gear it moves a bit, the linkage to shoves the magneto linkage moves up a small bit( fully advanced in youtube video below) and it does not continue to move as the accelerator or throttle is increased to WOT. IN the video I have included it shows the boat at full throttle with the engine off, what I was wondering was if it( timing/magneto linkage) did not advance enough at high RPM'S could this cause it to struggle and stutter at high revs. Could do with a few opinions thanks. Basically I think its not in sync. Compression is 110PSI on both cylinders and spark is bright Thanks

https://www.youtube.com/watch?v=DotYg2cSEbI
Click to expand...

I have a 50hp mercm 1985. Worked on it a lot last year. Similar symptoms under load. I wouldn't mess with the linkages if I were you. Mine was fuel delivery. Cleaned the carbs, adjusted the floats. Also had some issues with fuel delivery from the tank, especially when the motor sat idle in the sun while running the kicker. Seemed like I was getting air in the fuel line. Now I bleed the line before connecting to the motor then pump the ball. The same symptoms occurred when I forgot to open the tank vent. Just my two cents.. Good luck..
 
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