how to bypass Mariner 115HP 2+2 cylinder activation

[docster]

So my understanding is that this is mechanically controlled, no electronics. Is that correct? There has to be a way to bypass this system. I think its a horrible design! 2 cylinders are allowed to move at up to 1800 RPM without oil? thats just plain retarted. I have heard that just simply switching the lower carbs for upper carbs cause serious idle issues. Has anyone had any success bypassing this system? If so, what did you do?

I cant believe Mercury allowed this to be put into production, just seems so unsafe for the engine.

 

[jeffersondodson561]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

It is controlled by the throttle cam actuation, purely mechanical no electronics to bypass. If you think that is dumb ask why did Mercury buy Force!

 

[docster]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

so there is no way to bypass it with by changing/upgrading anything? im stuck with it?

 

[docster]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

here is what i was thinking to rid myself of it. Bypass the accelerator pump all together. Run fuel to all 4 cylinders equally and replace the bottom 2 carbs with uppers. then spend about a weekend fine tuning them to get them all in sync so they idle ok, and run well. would this work?

 

[boobie]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

I ran into this mtr 20 yrs ago and tore my hair out trying to make it idle on all 4 cyls until somebody told me it was designed that way. But I guess that would figure, as the same company made an outboard mtr that ran backwards so you could get reverse.

 

[cps22]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

I'm confused.....
I have the same motor, just 2005 and was told the 2+2 was just air flow at RPMs over a certain level. What throttle cam action causes the switch between 4 & 2 cyls?
I mean does the throttle cam reach some point where it pushes against something and then activates all 4 cyls?
http://forums.iboats.com/showthread.php?t=510067

 

[docster]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

basically yes. the cam activates the accerlator pump which sends more fuel carbs at cylinders 3 and 4 so they get enough draw to get firing. its a horribly moronic design. i would love to talk to the "engineer" that thought of this and ask him WTF he was thinking not sending oil to those cylinders....the pistons are still moving!

 

[79Merc80]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

The bottom carbs do not have an idle jet, that's all, there is still fuel/oil going through the carb and to #3 & #4, just not enough to make any power, so they still get oil. At about 1800 RPM (On a slow increase), there is enough vacume to bring in enough fuel to make power. When you hammer the throttle, the accelerator pump squirts fuel/oil in to get the bottom 2 online for pulling a skier. This design has been in their lineup from 1988 till Mercury changed over to 4-strokes, over 20 years.

 

[Faztbullet]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

But I guess that would figure, as the same company made an outboard mtr that ran backwards so you could get reverse.

Now Boobie, dont forget them people that made them "OMC" motors made one also that ran backwards (reverse) for counter rotation.....

It is controlled by the throttle cam actuation

Nope ...cam only works the accelerater pump.

so there is no way to bypass it with by changing/upgrading anything? im stuck with it?

Uhh...yep.

Run fuel to all 4 cylinders equally and replace the bottom 2 carbs with uppers. then spend about a weekend fine tuning them to get them all in sync so they idle ok, and run well. would this work?

Going to be a looooooooooooooooooooooooog weekend

I'm confused.....
I have the same motor, just 2005 and was told the 2+2 was just air flow at RPMs over a certain level.

That is correct.......

What throttle cam action causes the switch between 4 & 2 cyls?
I mean does the throttle cam reach some point where it pushes against something and then activates all 4 cyls?

The only thing cam does is activate the accelerater pump it has nothing to do with activative of the carbs...

basically yes. the cam activates the accerlator pump which sends more fuel carbs at cylinders 3 and 4 so they get enough draw to get firing. its a horribly moronic design.

Wrong...see above and 79Merc80 post as it is correct, the accelerater pump pump a squirt of fuel into bottom cylinder thru 2 injectors. If system is set up correctly and fuel pressures are correct you will not notice any delay or bogg

 

[cps22]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

Interesting information, I'll do some experimenting and report back.

Thanks,

CPS22

 

[boobie]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

Faztbullet, Yeah but that mtr ran backwards All The Time. Not just to put it in reverse. If I remember right, the same company that made the ob run backwards to get reverse also made a snowmobile the same way.

 

[Faztbullet]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

Yer right but you gotta admit them "dock buster" motors was a engineers dream come true, and nothing would touch em in their day. The 220ER, 250ER snow blasters did run backwards but it kept the drivetrain simple.

 

[boobie]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

Dream or nightmare?? Depends on how you look at it.

 

[72bronco]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

know thread is couple months old but know one really answered question are you saying put jets in bottom 2 carbs and they will work at idle?would love to have all 4 carbs working together thanks

 

[Faztbullet]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

Sorry but it wont work as people have tried it with no success. The engine I am told actually idles worse with all four working and try's to shake its self to pieces....

 

[CharlieB]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

Once the 2 + 2 system is dialed in, following the FACTORY service manual, most operators cannot tell the difference. Slow speed, mid speed, or WOT, it just works.

The adjustments are absolutely critical, without the service manual you haven't much chance it faking it.

Once again it just proves that "When all else fails, Read the Book!"

 

[Texasmark]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

So my understanding is that this is mechanically controlled, no electronics. Is that correct? There has to be a way to bypass this system. I think its a horrible design! 2 cylinders are allowed to move at up to 1800 RPM without oil? thats just plain retarted. I have heard that just simply switching the lower carbs for upper carbs cause serious idle issues. Has anyone had any success bypassing this system? If so, what did you do?

I cant believe Mercury allowed this to be put into production, just seems so unsafe for the engine.

Me neither and that's why I have a 90 triple on a boat rated for a 130.......I mean going from a 115 tower to 2 cylinders at low speed....puuuuuuuuuke!!!!!!!

 

[Texasmark]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

Dream or nightmare?? Depends on how you look at it.

How could it possibly be a dream? That's one reason the old 4 cylinder cross flow lasted so long.........smoooooooooothe trolling.

 

[Texasmark]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

Now Boobie, dont forget them people that made them "OMC" motors made one also that ran backwards (reverse) for counter rotation.....

Nope ...cam only works the accelerater pump.

Uhh...yep.

Going to be a looooooooooooooooooooooooog weekend

That is correct.......

The only thing cam does is activate the accelerater pump it has nothing to do with activative of the carbs...

Wrong...see above and 79Merc80 post as it is correct, the accelerater pump pump a squirt of fuel into bottom cylinder thru 2 injectors. If system is set up correctly and fuel pressures are correct you will not notice any delay or bogg

Cute reply!

 

[MercGuy]

Re: how to bypass Mariner 115HP 2+2 cylinder activation

I've got a 1998 115 2+2 that I purchased new in 1999. I have 980 hours on it now.

At one point I didn't like it, but then I read the owners manual and learned how to link n sync it to get everything adjusted properly. It's run great ever since.

I dont know that I would purposely go looking for a 2+2, but I wouldnt avoid one either. They run just fine when set up properly.