1995 135 Merc. runnign rich and bogging out

[GITDNET]

I have a 135 Mercury that I got last season, and a few trips out it started to bog out when I would accelerate slowly, but it would only bog out from maybe 8 to 10 mph then it would smooth out after I gave it more throttle slowly. If I tried to gun it while it would start to bog out then it would die. I just rebuild the carbs, installed new needle and seats, replaced the primer bulb, fuel filter, and rebuilt the fuel pump. I took it into a shop and had them check the compression and all was good. The first trip out I went to the Delta, and it ran great, smoked a little more than I would like but no bogging issues. Last weekend I took it up to a sierra lake and it started to bog out again and smoked like it was running way to rich. Now, when I rebuilt the carbs, I turned the Idle mixing screws out 1 1/2 turns from a lightly seated position. Question...When I open up the mixing screws (counter clockwise) does that give the motor less fuel or more? Could this be the problem??? Any input would be great... Thanks everyone..

 

[Chris1956]

Re: 1995 135 Merc. runnign rich and bogging out

Opening up the mixture screws (CCW) richens the mixture. That motor has six idle mixture screws. It sound like maybe not all are set properly. I was able to set the ones on my '93 merc 135HPV6, so any one should be able to do it. I would recommend fresh fuel, if you run on premix. Take your time. First set the mixture screws to achieve max idle speed. Now start to test for acceleration. if she stumbles, open the top carb screws 1/8 turn and try acceleration again. Next open mid carb mixture screws 1/8 turn, followed by bottom carb screws, testing acceleration after each adjustment. Repeat until you have good acceleration and resonable idle.

 

[GITDNET]

Re: 1995 135 Merc. runnign rich and bogging out

Thanks, I'll try it, but does each carb have to be adjusted the same amount of turns on the mixing screws? So can the top carb screws be out 1 1/4 turns out and the middle carb be 1 1/2 turns? Will different adjustments on each carb cause engine damage?

 

[Chris1956]

Re: 1995 135 Merc. runnign rich and bogging out

Each carb bbl mixture screw needs to be customly adjusted. Since it is only an idle adjustment, damage cannot occur if it is misadjusted.

What you will find is that the lower carbs run a bit richer due to gravity. Therefore the top carb will likely be set a bit richer than the mid carb, and the lower carb a bit leaner than the mid carb.

 

[GITDNET]

Re: 1995 135 Merc. runnign rich and bogging out

Thanks Chris....I'm going to try this this weekend out at the lake. Should I start each screw out at 1 1/2 turns out from a lightly seated position for a starting point? Per the manuals directions?

 

[Chris1956]

Re: 1995 135 Merc. runnign rich and bogging out

Yes start at 1-1/2 turns out. Start richening them, top carb first until you max the RPM, and then adjust to richen additionally for smooth acceleration.