What would cause a 6 cylinder to fire on only one cylinder? being taken for A RIDE?

[fostersds]

I have a 1984 mercury 115hp inline outboard and have a problem with it. I got it tuned up this spring and on the clamshells it was running great. I took it to the lake and it seemed not to throttle out of idle. I took it to the local marine repair shop and they just called me and stated that they got spark only on one cylinder. They thought it was the stator but weren't sure. Would a bad stator cause this or is there something else that would cause this? The repair shop didn't sound positive that this was the problem, said it might be the coils or switch box. Seems to me that they could test them to be sure. Am I off base or what? What would cause this problem?

 

[alldodge]

Had a look to help, but you need to be in the outboard section

Hey GA_Boater can you help

 

[GA_Boater]

Moved to Merc outboards.

Any shop worth it's salt should be able to test the ignition components. I wonder if the shop doesn't like to work on the old motors?

CDI has a test procedure used by many of us - https://issuu.com/cdielectronics/docs/practical_ouboard_ignition_troubles

 

[Fun Times]

If they have the experience and the right info, they should be able to keep looking to locate the problem.

Maybe ​have them check out the very helpful troubleshooting info/guides provided by CDI Electronics.

http://www.cdielectronics.com/technical-support-documents/

Got you moved over to the correct sub-forum for additional help.

Good luck.

 

[fostersds]

I apologize for posting in the wrong area. I appreciated the link to the info.
I was talking to my wife who dropped off the boat since I was working and she said the shop had a sign up that they do not work and motors older than 1978 so you may be right about them not wanting to work on them. I am having them replace the stator and am hoping that will solve the problem. However after that, I think I will try tackling it myself with a whole lot of help from here, if you all are willing.

 

[GA_Boater]

No problem, Foster. We have lots of sections here and threads are easy to move.

Make sure you get the old stator back. If it isn't the root of the problem, you will have a spare.

 

[Chris1956]

I doubt a 6 cylinder motor would actually run on one cylinder. If the shop actually said that, they should be avoided, IMO. Take a compression test and using a timing light, take a spark test. Post back results.

Ironically, the ign system in your motor was used until sometime in the 2000s, so they should be familar with it.

 

[fostersds]

Ok. I will try to do those items. I am more familiar with car engines but can probably figure it out. They also said it might be the coils or switch.

 

[Chris1956]

They seem to be grasping at straws. Six coils went bad....

 

[fostersds]

That is what it seems to me. Either they don't know what is wrong or they do not want to work on an older motor. I figure I will let them replace the stator and I can replace the rest if need be.

 

[Chris1956]

Get the old stator back from them, after they change it. I guess I am cynical, but I suspect they won't really do any work and just bill you.

 

[fostersds]

It is nice to hear that i am not the only cynical person around. I am planning on getting the old one back. To tell the truth I don't even know if what they told me was true. All I know is the motor ran great when I had it on the clamshells and would start just fine, even in the lake. However, when I went to accelerate, nothing happened. It didn't die, just seemed not to move out of idle. I played with the carburetors but still would not increase acceleration. Figured I would let them look at it but nows seems like a mistake.

 

[racerone]

A common problem with these motors is " too lean " on the low speed mixture.-What that means is they idle very nicely but there is not enuff fuel to get to the high speed circuit.------The solution if that is indeed the problem is to open the 3 low speed mixture screws 1/8 turn at a time and test run again in the lake.--Costs nothing to try that.

 

[fostersds]

That sounds more reasonable and makes more sense. How the repair shop determined it was one firing on one cylinder, I don't know. I will try that when I get the boat back. Is there any way they could make that mistake or might I be missing something?

 

[Chris1956]

I find it easy to believe the shop is not aware of the nature of the carb adjustments, as their techs were likely in diapers when the motor was produced.

I find it hard to believe they do not understand the ign system, as it is real common, and was used for a long time. That ADI system on the larger Mercs, was first used on the 1976 85HP Merc, and continued to be used until the mid-late 2000s.

 

[JDusza]

IMHO...dump the repair shop.

 

[fostersds]

Well, actually they told me that the internal wiring harness was fried and that the harness is no longer available. I was able to find one on ebay so I am taking a chance with it. After thinking it over and discussing it with my wife, we decided to cut our loses and we bought another boat. However, i have a lot to learn about it since it is a inboard. It is a 1985 Sea ray with a new rebuilt 350 in it.

 

[Chris1956]

The engine wiring harness should be easy to find on the web. I got 8K hits when I searched.

Replacing the Stator replaces most of it. Replacing the trigger replaces more of it. The balance of the harness is a couple of wires, and is avail as well.

 

[fostersds]

I did find the wire harness on eBay so I think that the repair shop probably just didn't want to work on it. So I will get the parts one by one as need and try to fix it myself. The shop did put in a new stator and didn't charge me so I guess I can't complain about that too much.
What exactly is the trigger? Please excuse my ignorance.

 

[Chris1956]

The trigger is a round device that sits under the flywheel. It tells the switchboxes when to fire. Trace the wiring back from the switchboxes and you will find the trigger.