merc 115 inline 6

[Dassault]

79' inline 6 115. Took the boat out this morning expecting a good trip. Last week i thought i had my problems solved however i obviosly didn't. Putted out and fouled a little but cleared out and ran pretty good. Then i went to ski. The motor bogged down and wouldn't go. Cleared it out, same thing........ Well, adjusted mixture and tried again, again and again. All the while adjusting the mixture. I am running AC V40FFM plugs and they are fouling out. Is this the right plug? I have put about three sets in this summer. I have rebuilt the carbs, new needle and seats, floats, fuel bulb, pump, cleaned tank out. This motor runs awesome when you get up on plane, i can do about 48 on a 19 pitch prop But it will not go under load of a skier. Maybe a linc and sinc but i couldn't see that fixing it but i don't know. Any suggestions?

 

[Dassault]

Re: merc 115 inline 6

Sometimes it does go and pulls a little weak but its gets the skier up, and runs pretty good once on plane. Its a 25/75 ratio of go to no go on starts.

 

[2cycle]

Re: merc 115 inline 6

Sometimes it does go and pulls a little weak but its gets the skier up, and runs pretty good once on plane. Its a 25/75 ratio of go to no go on starts.

The factory calls for Champion L76 V surface gap plugs. I would try those. The heat range is crucial in the inlines as they will burn up with too hot a plug from what I've heard. The mixture screws should be about 2 1/4 turns CCW from a lightly seated position.

 

[jimmbo]

Re: merc 115 inline 6

A link and sync would not hurt. Carbs might need cleaning. I had an 84 115 that hated the ski rope. It would take off fine, pull like a tractor, but as soon as you hooked a ski rope to the pylon it would bog and die. This was when it was set to specs for the link and sync. The dealers tech changed the primary pickup piont, richened the carbs and it was a totally different engine.

 

[Dassault]

Re: merc 115 inline 6

I have rebuilt the carbs twice and they are as clean as a whistle. I sealed the threads around the seats and solved my fuel leakage problem last week and now its down to a narrow list. I have cleaned the cap and rotor, i have not checked comp. but it runs amazing at fuel half, anywhere on plane so i am guessing it not too shaby. Thanks 2cycle for the plug info i will try those! What did they change the primary pick up point to? I have been richening the carbs it seems to help but my plugs keep going out on me! Thanks!

 

[Dassault]

Re: merc 115 inline 6

Its not always running like a tractor either, it will hesitate and miss, jockey the throttle and it will usually slowly clear out and go.

 

[Dassault]

Re: merc 115 inline 6

Also my idle screws are about 1 3/4 or a little closer to 2 out and it idles rough there, rich setting. Pulled out my plugs and the top four were pretty black and oily, bottom ones (carb 3) not as bad but still showed dropplets of oil. In my experience i have never seen plugs with oil on them such as this motor. Anyone else ever have any oil on there plugs? I am running a 50:1 ratio with quicksilver syn., maybe it is my pickup, fouling the plugs when trying to take off?

 

[Plainsman]

Re: merc 115 inline 6

Screws should be set to 1 1/2 turns from a soft seat. Go a 1/4 turn till it stumbles, then back an 1/8 of a turn. The oil in the plugs could be from running it rich. The gas burns but not all the oil.

 

[2cycle]

Re: merc 115 inline 6

I think the primary pick up point is 4-6 degrees BTDC. That is for my distributor motor, but I think you have ADI ignition? It is probably still the same or close. Hopefully someone will verify.

 

[Dassault]

Re: merc 115 inline 6

That sounds about what the seloc manual said last i read.

 

[Dassault]

Re: merc 115 inline 6

Also i checked the compression while the motor was cold and it was about 103-105 on all cylinders, so i assume they are all okay, realizing that compression increases with heat (suprinsing they were all the same,give or take 1 or 2 psi the). I have been using ac delco V40FFM plugs, however, just bought some autolite plugs that match the champion L76 v plugs to try out tis week.