Anybody good with merc's?

S

Stevie g

New member
we just recently put our v20 in the water. it has an 1985 merk 200hp v6. at 1st it ran great but then it would slowly rpm down and die then it would be a bi*ch to start back up. when we got it out of the water i tested to see if all the cylinders had spark. oddly all the plugs on the port side sparked perfectly, all 3 on starboard had no spark at all. I'm thinking maybe control box? im really lost when it comes to boat engines so im hopeing someone can help me out! thanks
 
Ferm, Bigshrimpn, or Spare will be along shortly to have you fixed up.

I will give it a shot in their absence.....DO NOT LISTEN TO ME!!!!

Could be the power pack for that bank of cylinders or it could be the reverse cut out switch that someone else had trouble with recently.

Or something else that I don't know about.....wait for the experts to answer.
 
Sounds like a switch box gone bad to me. The easy way to diagnose would be to swap switchboxes from one side the the other and see if the problem moves with it. Ferm or Shrimp will be along shortly with a more detailed answer.
 
i would agree switch box you have two of them one for the left side plugs and one for the right side its easy to replace could also be the stator but sounds like switch box to me
 
Knock on wood, my MERC has been trouble free. If I had to guess I would say switch box though. Common problem for the MERCS to lose em. RAPAIR/CDI is regarded as being the better replacement for the switchboxes.
 
thanks guys for the quick response. i didn't know the switch boxes were interchangeable.. that will definitely be my saturday morning project, switching them around. i'll keep you guys posted. thanks again!
 
bad news guys i just switched both boxes around and i'm still getting no spark on the starboard. so now i eliminated the idea of a bad switch box what should be next on my trouble shooting?
 
steplift20 said:
if its not the switch box check the stator,im not sure how to do that but im sure someby will tell you
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yep sounds like one side of the stator is out, you can ohm out the stator but i always thought that test sucked. best test to do is to DVA the stator but you need a special meter or an adaptor from cdi elec to do that. or you can ghetto dva the engine like you did just you dont get any cool numbers to look at. before you drop 300+ on a stator check the grounds and if they are good then thats most likely what it is.
 
is it hard to somehow remove the stator and take a look at it? i seen them on the internet for about 150$... if it isn't the stator or bad grounds what could it be.
 
Not having worked on mercs

randlemanboater

Could be the power pack for that bank of cylinders.

Does that thing have 2 regulators or powerpacks that are controlled by the stator?
If so and if the part numbers are identical, swap them around and see if the spark problem moves to the other side.
 
i hate to say this but if i was you the good thing is its not working so it would be easy to find the bad thing is i think you should take it to a marine shop and let them diagnose it for you unless you can diagnos the stator yourself i replaced mine 3 times or the marine shop did it you need special tools also it would be garranteed by them could be a bunch of things
 
I would reccomend you wait for Bigshrimpin to pop in. He sold me some MERC parts for one of mine a couple weeks ago. Plus he knows the MERCS. The bare minumum though you need a peak reading volt meter, or a DVA with a PRV adapter from CDI.
 
Sure sounds like a bad switchbox to me. No spark on one side is almost a dead give away. Make sure they are both grounded. If you 100% positive that your didn't make a mistake swapping them . . . then There is a test for the trigger and stator in the manual using a multimeter . . . You won't have to pull the flywheel to test them . . . just disconnect them from the switchboxes and check for continuity . . . specs are in the manual. If you need me to scan some pages . . . . I can do it. I have TONS of 9/16amp merc parts, so don't go buying anything new. I have 30+ switchboxes and several stators and triggers for that engine.

How's the wiring (harness to coils, trigger wires, stator wires)?
 
Stevie g said:
bad news guys i just switched both boxes around and i'm still getting no spark on the starboard. so now i eliminated the idea of a bad switch box what should be next on my trouble shooting?
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boxes sounds good, still sounds like the stator. it probably isnt the trigger because that usually would give you two dead cyl, one on each bank. and if you still want to be sure bring it to a shop and tell them you want them to put their meter on the yellow wires tell you what they find. they probably wont charge more than 50 dollars.
 
bigshrimp, im going to try this in that link you sent me

No fire on the 1,3,5 or 2,4,6: Swap red and red/white wires, also blue with blue/white wires. If the problem moves to the other set of cylinders, the stator is at fault. Disconnect rectifier and retest. If the engine fires normally, replace the rectifier. If no change, we recommend replacement of the stator. If you replace the stator and the problem remains try another flywheel, if possible.
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I'm a bit confused. does this mean i leave the whites and black/yellow stripe alone on both switchboxes. and switch the reds and blues between the 2 switchboxes?

If thats what there telling me to do it seems easy enough. i just want to make sure 1st. thanks again.
 
i switched the leads from the stator on the switch boxes now the starboard has the spark and the port doesnt. following that website i disconnected the rectifier. taped off the wires going into it and rechecked everything. one bank of cylinders still isn't getting spark, so now i believe it has to be the stator. bigshrimp i'm interested in buying one off you depending on how hard it is to replace myself.
 
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