115 Mercury 1988 Power/Smoke Probs.

[TGattis]

Alright here is one for the pros:<br />1988 Merc 115 inline 6 <br />23 pitch stainless prop dia?<br />rebuilt powerhead<br />rebuilt/readjusted carbs<br />removed water from tank<br />This thing is driving me nuts it ran perfect for 2 miles once then it loses power I readjusted the timing now it runs great until it gets to 4000rpm then it starts to spit and sputter and lose power until I back off the throttle.I think it may be the coils,stator/trigger,switchboxes or a combo of any two. It also smokes quite a bit more than my old Yamaha did it this normal for a Merc?<br />I looked through a few pages and didn't see any other posts that portrayed the same type problems so maybe some of you REAL geniuses have an answer.<br />I mean geniuses in the good way.

 

[The Marine Doctor]

Re: 115 Mercury 1988 Power/Smoke Probs.

If I am not mistaken you should have a small black box mounted just above the carbs. This box is for timing. It may be functioning improperly and knocking your timing back.<br /><br />Or a Fuel delivery problem.<br />TMD

 

[TGattis]

Re: 115 Mercury 1988 Power/Smoke Probs.

Naw Doc no little black box there although it does have the idle stabilizer box mounted on the front strut/support in front of the carbs but , it is disconnected at the recommendation of a Merc mechanic "it doesn't do that much to help anyways" as he put it.We thought it might be causing the problems.My next idea is to swap the switchboxes and see if it is in the "high speed box". Any other ideas?Suggestions?<br />My best solution is a new Yamaha!$$$$might have to lower my standards and go with a Rude or Johnson though.less$$$$

 

[The Marine Doctor]

Re: 115 Mercury 1988 Power/Smoke Probs.

Hmm...the stator controls high speed....but if you are already hitting 4k then I doubt its the Stator. Does your Tech have access to a DVA testor...if he does then there is no need to swap parts...he should be able to test and replace.<br /><br />As for an engine to relace the ailing one you have now...I would look towards buying the 115 Optimax...great engine.<br /><br />TMD

 

[TGattis]

Re: 115 Mercury 1988 Power/Smoke Probs.

I don't khow if he has a DVA tester but I'll ask.<br />My thoughts are leaning more towards the switchboxes or a coil dropping out after it gets uder a load as it doesn't do it while it's on the muffs.wierd huh?Might be it has to much prop?Boat is a 17' Sea Chaser RG Copy weighing about 900#s the few (opperative word)times it ran perfect it would run 65+mph now tops is 48 mph although the wife likes the ride at 30 a little to much chine walk to make her comfy.I did the ohmeter test on all the components and they all tested out within spec.(If I read the meter right).

 

[The Marine Doctor]

Re: 115 Mercury 1988 Power/Smoke Probs.

Were the puddlers changed on the intake side?<br /><br />Little plastic restrictors that are used to bleed the exess fuel off.<br /><br />Should be 5 of them...if they are gone they will inturn flood the cyl's below them.<br /><br />TMD

 

[jdkzrt]

Re: 115 Mercury 1988 Power/Smoke Probs.

Cracked / Broken reed???<br />Is it smoking all the time, or just after you start the engine???

 

[TGattis]

Re: 115 Mercury 1988 Power/Smoke Probs.

TMD, no idea what puddlers are I didn't do the rebuild, Bought the boat from the man who did.<br /><br />JDK, It only smokes after I start up until I get going a good bit. Kinda like the valves aren't seated good yet. It will smoke like this every time it sits for an extended period 1-2 hours minimum.<br />Also I am going to replace the impeller. Is this as big of a pain as a 15hp evinrude or should I just pay the guy 75.00 to install it for me.