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Not reaching high rpm's under load.

B

Beagleman

Regular Contributor
Good day folks, this is my first time even posting a question. *So have patience if I suck! * Lol

I got a 40 hp mariner (40 E * *6E95 * *104752), not sure of year (chances are mid-late 80's) 2 cylinder. *Excellent compression (120 per hole), and fires right up after 1 or 2 pulls. *The issue lies in achieving any higher than 1/3 of the rpm's of w.o.t. *This only happens when it's in gear in the water. However, that being said i get a slight few more rpms if i open the choke as im going. *When in neutral, she'll rev up as high as you want it to. *She idle's fine with the choke on, but doesn't idle while choke is closed. *

In respect to what i've done with it (as in trying to get to the root of the problem) i hought i was losing spark. *so, i started it at night (seen nothing) and tested to see if there was spark the old fashion way. *lol. *So, i tried changing the coil ( because i have an extra). *I'm not sure about in forward (because I never had her in the water since) but for the rest it's the same (I.e. I get a shock from the top spark plug boot only but a bit less, she still fires up real quick, and to be honest it sounds pretty good).

so, where should I start, I'm somewhat knowledged of these (been on the water recreationally/commercially for 25 years) but I ain't no tech. *

I appreciate any help I can get.

thanks guys*

robby
 
40C E6E9-103919 - 6E9-1047981985

You have a 40HP Yamaha built Mariner.Copies of Yamaha's own,older 40FM's The "5" is probably an S,meaning it's short shaft.Not having much of a clue about these outboards,but it does seem to me to be fuel related.Clean carb,check compression. Spark should jump 3/8". Good luck
 
Check the reed valves behind the carbs and manifold for damage. My RPM were down and found a chunk of plastic holding one reed open.
 
haventaclue said:
40C E6E9-103919 - 6E9-1047981985

You have a 40HP Yamaha built Mariner.Copies of Yamaha's own,older 40FM's The "5" is probably an S,meaning it's short shaft.Not having much of a clue about these outboards,but it does seem to me to be fuel related.Clean carb,check compression. Spark should jump 3/8". Good luck
Click to expand...


Thank you very much. I appreciate it. Do you know what gap I need on the plugs? Do you mean spark jump as in "taking plug out of piston hole, holding 3/8 inches away from a ground, pulling it over and seeing if it reaches the ground"?

Im going on the water tomorrow, I'll let you know how it works out?

All the best. Robby
 
Thank you very much. WOuld you mind sending me a picture of both the reed valves and manifold(s) so I know what i'm working with here?

Thanks again.

RObby
 
She got 120 compression on each cylinder. I get à shock from thé top boot, not bottom, what does this mean? I Will Check butterfly now and promtly reply.

thank you vers much
 
I cleaned out carburetor, used some seafoam, and I was steaming along today, heard a sputter and up she went. It's like something was inside of it broke loose. She runs like a top, and even idles without the choke.

thanks guys, u all rock.
 
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