older Mercury 115 will idle but will not go past about 1500 rpm's

[timmathis]

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

Mewrky, what year is this critter? Distributor or ADI ignition?

 

[kylestyle]

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

ok I know that no one has responded to this since 2006. But I have the same problem. 1988 mercury 115 inline 6. Starts Fine, revs up just fine in neutral. However once in gear motor will not pass 1500 rpms just seems to bog. I have checked the fuel pump, fuel filter, ohm out the stator, ohm out the coils, checked the compression in all six cylinders (120 psi), put new spark plugs in, and also checked to see if all three butterflies on the carbs were opening together. The next thing I am gonna do is clean out the carbs again, I have not done that yet because they were rebuilt a couple of months ago. I was curious if this sounded like a switch box issue? Any help would be awesome!!

 

[njrextreme]

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

The thing with these motors is in N, it will rev, but not near as fast and crisp as it should. In the water, you have a load on it. Now you can tell its not running well. The switch boxes run 3 cyls. each. If one box is bad, then your only running on 3 and yes it will sound like it is reving up in N just fine. I would recheck the stator, trigger, and switch boxes. They seem to go bad on alot of merc mariner i6 motors w/ age. Do some searches, alot of guys have your same problem. My 86 90 had the same problem. Ran great or so I thought in the driveway, and would not have the power to plain its self out in the water. I replaced my complete ing. system and it was fixed. Not that you want to go that route, but I elimitated the guessing game.
NIck

 

[asm_]

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

ok I know that no one has responded to this since 2006. But I have the same problem. 1988 mercury 115 inline 6. Starts Fine, revs up just fine in neutral. However once in gear motor will not pass 1500 rpms just seems to bog. I have checked the fuel pump, fuel filter, ohm out the stator, ohm out the coils, checked the compression in all six cylinders (120 psi), put new spark plugs in, and also checked to see if all three butterflies on the carbs were opening together. The next thing I am gonna do is clean out the carbs again, I have not done that yet because they were rebuilt a couple of months ago. I was curious if this sounded like a switch box issue? Any help would be awesome!!

If I was to post the description for the motor I'm working on, that would have been it. Except, replace 1500RPM with 1800RPM and 1982 instead 1988.

I have every single test you have done, and moving on the cleaning the carb and float bow. While I was doing all the tests, I did noticed the lower carb barely suck any air. That's something you may want to check.

b

 

[altamimi]

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

hi ho many rpm could be 5 or 5 an half

 

[kylestyle]

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

well at least I am not the only one with this problem.

altamimi
hi in your engine it become hot water

...I guess your asking if hot water comes out the motor once it warmed up.
Well its pretty warm but not scalding hot.

 

[kylestyle]

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

Re: older Mercury 115 will idle but will not go past about 1500 rpm's

Ok so after checking spark in all six plugs it looked like 3 cylinders had a very weak spark on one of the switch boxes. So I went ahead replaced that switch box. Now the engine has a nice spark in all 6 cylinders at idle. The engine even Idles really nice. However now in N and under load the engine only revs up to 3100 rpms. which is twice as good as before. You can here the motor run perfect all the way to 3100 and then you can tell it just bogs. Im at a loss any suggestions on what to check or replace now would be great.