Help with 200hp merc running rough.

CharlestonSC · #1 06-25-2011, 06:51 PM

1992 200hp black max.
Just got it in the water today first time this year.
Mods I did this winter.
Added 2nd fule tank, but have not used it.
changed stator and voltage regs, they didn't go out on me but the few windings were loose so I replaced it before it fales me.
Did power packs last summer.
It is running rough, pulled wires off when running and no change or not much if any change when I pull off the bottom left and bottom right spark plug wires.
you can for sure tell when I put the other 4.
Idles a bit rough but not to much different that it ever ran.
But won't get above 4K rmp and it sound like it's missing a few cylinders.

Any thoughts where I should start???,

Spare I'm in MT pleaseant have any time to check it out?
Thanks

spareparts · #2 06-26-2011, 08:06 PM

I'd be happy to look at it for you, just not this week, I'm slammed

CharlestonSC · #3 06-26-2011, 08:18 PM

Thanks, I dragged it back to Greenville, I'll see if I can tinker with it through the week.
I checked spark on all plugs, they looked good.
Wondering if because it sat for 6 months without running if the carbs are gummed up, and if that would make it run rough?
I did put fresh gas in it. and changed the filter on the water seperator.
let me know what you think.
Thanks

spareparts · #4 06-26-2011, 09:59 PM

90% of what I've been doing this year has been carb rebuilds/fuel injector issues/ fuel systems. I think you are on the right track

Destroyer · #5 06-27-2011, 01:40 AM

Have you run a compression check yet? If they are all near each other then I'd suspect dirty carbs...

CharlestonSC · #6 06-27-2011, 11:44 AM

Bad new stator CDI, I put my old stator back on and runs great.
I put a new CDI stator on as my old stator was still working but one side of it must have got realy hot at one point as the wires were discolored, and a few coils were loose, Preventive maintenance bit me in the but, trying to head off any stator issues, and with the new one was no good going to the power packs, my voltage when running was about 14v so I guess the charging part was ok.
They are sending me a new OEM Merc stator as a replacment, we will see if this one works.
thanks for the input.

draglink · #7 06-27-2011, 05:22 PM

Same issue I had with mine....running rough at idle. Narrowed it down to stator. Old stator was aftermarket but looked brand new. I got a new Quicksilver one- they are supposed to be better and that took care of it.

CharlestonSC · #8 06-28-2011, 06:11 AM

Do you know why they build the 40amp stator in 2 20amp sections?
Is that supposed to make it so you will not completly break down?
I was told that if your stator goes you are sitting dead in the water.
Did you see my the last pictures I posted of my Sport 20 in the Transom rebuild post I started.

draglink · #9 06-28-2011, 06:39 AM

I have no idea, but that makes sense....Maybe your dead in the water if you have a total failure? All I know is I had very weak spark on 2 cylinders at idle...causing her to idle rough as hell. First replaced the 2 power pack box things, then finally the stator. According to my buddy/Merc mechanic its a VERY common thing to go bad these days....like everything else---they dont make them like they used to!

Destroyer · #10 06-28-2011, 11:04 AM

Quote:

Originally Posted by draglink

I have no idea, but that makes sense....Maybe your dead in the water if you have a total failure? All I know is I had very weak spark on 2 cylinders at idle...causing her to idle rough as hell. First replaced the 2 power pack box things, then finally the stator. According to my buddy/Merc mechanic its a VERY common thing to go bad these days....like everything else---they dont make them like they used to!

Ever think that it's intentional? Why build something that's gonna last forever when you can build something that has to be replaced every couple of years...at a significant price.