Power loss 115 merc.....STILL!

[Madpole]

Hi all! Well it is starting to get warm again here and I have finished my restoration project.
However, I have not been able to find and fix my power loss under load problem. (only acheives 1/2 throttle) It actually runs very smoothly unless I try to give it more than about 1/2.

I have performed all of what was suggested by the great guys on this forum with no change in results.
Here is what has been done to date on my 1985 inline 6, 115 HP Merc:

Good fuel, New primer bulb and lines. Vent to gas tank clear. Carb's cleaned and rebuilt. New rectifier. Good compression all cyl's within tolerance. Good spark (I built a test jig) all cyl's. And one switchbox was replaced by previous owner.

Now....when underway if I press the enrich button on the keyswitch the motor bogs down as if being flooded! Which it apparently is! Squeezing the bulb has no effect so I think the fuel pump is ok.

Does anyone have a suggestion where I should look next? Is there a way to test the stator to rule that out? I don't want to spend money on something that doesn't need to be replaced.

Please...any help is appreciated.

Thanks, Madpole

 

[mr 88]

Re: Power loss 115 merc.....STILL!

Have you done the link N sync procedure ?

 

[Madpole]

Re: Power loss 115 merc.....STILL!

I have no idea what that is.

 

[Madpole]

Re: Power loss 115 merc.....STILL!

Thanks mr 88. I looked it up in my Clymers manual.
However, the carburetor rebuild, primer and line replacement was done by a boatshop mechanic. I would hope that he would know if there was a problem with timing/carb sync. (although the previous owner was not happy with his work since the same problem still existed after getting the boat back.) I think the mechanic wanted to sell him on a new stator install job and he was done spending cash on this boat, and sold it to me.

Since I don't have the proper dial indicator to do a static check on TDC is there some way to tell if the setting is "close enough" to rule that out as the problem?

 

[BonairII]

Re: Power loss 115 merc.....STILL!

Thanks mr 88. I looked it up in my Clymers manual.
However, the carburetor rebuild, primer and line replacement was done by a boatshop mechanic. I would hope that he would know if there was a problem with timing/carb sync. (although the previous owner was not happy with his work since the same problem still existed after getting the boat back.) I think the mechanic wanted to sell him on a new stator install job and he was done spending cash on this boat, and sold it to me.

Since I don't have the proper dial indicator to do a static check on TDC is there some way to tell if the setting is "close enough" to rule that out as the problem?

Sounds like the mechanic would make more money selling a new motor....so he wouldn't be inclined to do the "link-n-sync"(and make very little money).

Get yourself an OEM manual....it's much better than Clymer, Seloc, etc.

I'm still guessing that you have a spark advance issue.

 

[Madpole]

Re: Power loss 115 merc.....STILL!

Thanks BonairII.
One thing I have not mentioned, during some of my initial tests on the lake the motor "took off" momentarily, like it was going to run, only to revert back to 1/2 speed. I have not been able to duplicate this event on demand. It sometimes acts like it wants to run harder with the enrich valve activated but most of the time just floods and chokes. This tells me there is an "intermittent' problem in the system. Which I think would rule out a mechanical timing setting which should be locked in place.

My manual troubleshooting guide has a section on removing the idle stabilizer...could this be my prob? Do you still suspect the spark advance?

 

[Laddies]

Re: Power loss 115 merc.....STILL!

Remove the idle stabilizer and test the ign. system as it sounds like you are loosing one side of the high speed winding in the stator but the low speed winding is OK and givse you spark at idle. You probably won't be able to find it without a DVA

 

[Lone Duck]

Re: Power loss 115 merc.....STILL!

Thanks BonairII.
One thing I have not mentioned, during some of my initial tests on the lake the motor "took off" momentarily, like it was going to run, only to revert back to 1/2 speed. I have not been able to duplicate this event on demand. It sometimes acts like it wants to run harder with the enrich valve activated but most of the time just floods and chokes. This tells me there is an "intermittent' problem in the system. Which I think would rule out a mechanical timing setting which should be locked in place.

My manual troubleshooting guide has a section on removing the idle stabilizer...could this be my prob? Do you still suspect the spark advance?

temporally disconnect idle stabilizer and run the boat ,You will soon know. With all the work that has been done a link & sync should be done regardless.

 

[Madpole]

Re: Power loss 115 merc.....STILL!

temporally disconnect idle stabilizer and run the boat ,You will soon know. With all the work that has been done a link & sync should be done regardless.

Thanks Lone Duck.
I will try that as soon as this lousy weather clears.
Madpole

 

[Lone Duck]

Re: Power loss 115 merc.....STILL!

Thanks Lone Duck.
I will try that as soon as this lousy weather clears.
Madpole

What lousy weather? It is sunny -8 and 3 ft snow on the ground here, beautiful day!! Not boat weather for another 30 or so days though.

 

[Lone Duck]

Re: Power loss 115 merc.....STILL!

Oh! I forgot to mention. Laddies has gave you a wealth of testing information. Print and keep it.

 

[Madpole]

Re: Power loss 115 merc.....STILL!

Thanks to all of you guys for your help. I will come back and report what I find.

By the way Lone Duck I'm in Georgia and we have rain and storms through the next couple of days. Sorry about your location......BRRRRRRR!

 

[CharlieB]

Re: Power loss 115 merc.....STILL!

Laddies has pointed in the direction you need to follow.

Download and study the CDI Ignition Troubleshooting Guide (free).

CDI Electronics Practical Outboard Ignition Troubleshooting

Follow their clear detailed directions how to test your ignition.

Lastly, check throttle cable with the engine OFF, move the throttle control to WOT then look down the carb throats to see if the butterflies are open fullly, flat.

 

[Lone Duck]

Re: Power loss 115 merc.....STILL!

Laddies has pointed in the direction you need to follow.

Download and study the CDI Ignition Troubleshooting Guide (free).

CDI Electronics Practical Outboard Ignition Troubleshooting

Follow their clear detailed directions how to test your ignition.

Lastly, check throttle cable with the engine OFF, move the throttle control to WOT then look down the carb throats to see if the butterflies are open fullly, flat.

Yup! Link & sync

 

[quicktach]

Re: Power loss 115 merc.....STILL!

I'd do the link & sync first. If that doesn't do it, you're into electrical tests...stator and trigger too (could be loose/moving). check all wiring for shorts, rubbing, burnt spots, good grounds. If you can't get over 1/2 throttle, chances are it's not advancing ....either mechanically or electrically. Could be a coil breaking down.