Merc 20hp 200 issues

[Ramair]

Hi, I have a Merc 20hp 200 which is a 1978 I believe ser#7061406. I'm looking for some advice on it. It's been difficult to start and when if finally starts to run the idle is erattic. I've played with the low speed screw to try to get a good idle but just can't dial it in.

I just did a total Carb rebuilt/clean. Jets gaskets etc. after reassembling the carb I tested to spark and noticed that the top plug (#1) was intermittently firing then seems to not fire at all. The bottom ply fires consitantly and strong. I tested the ign coils as per manual and they test ok. Plugs and plug wires are ok.

So, my question... should I pop the flywheel and test the stator/trigger etc or look at the switchbox as possible remedy.


Also, seems alot of parts for this engine are N/A. Are there any aftermarket parts places to source ignition parts?

Any ideas/suggestions would be greatly appreciated.

 

[JUSTINTIME]

Re: Merc 20hp 200 issues

test the stator and trigger
do ohms and volts

 

[Ramair]

Re: Merc 20hp 200 issues

Thanks for the quick reply JIT

I'll be checkin them later today and post what I find.

I was reading somewhere on here that the switchbox would be the likely cause. The other post mentioned that the stator/trigger wouldn't cause just one cylinder to die. Does that sound correct?
Can you tell I'm kinda new to the outboard repair process...haha..

 

[Laddies]

Re: Merc 20hp 200 issues

Ramair, chance are it,s a coil or switch box. the trigger windings act on both cyls as does the stator' you can ck the coil simply by changing the 2 input wires to the coils and see if the problems stays the same or moves, if it moves it's the switch box if it stays it's the coil

 

[Ramair]

Re: Merc 20hp 200 issues

Thanks Laddies, Guess what... you're right....Tested the stator and trigger today and both check out ok.

The problem does move when the coil wires are swapped with each other. So, I suppose I'm in the market for a switchbox now.

Thanks again for the quick replys guys This engine has been a bit of a time consumer not to mention makin my right bicept much larger than my left from pulling it over so many times..haha...(Thought---I'll have to alternate arms..lol..)

My dealer says I can get a good aftermarket SW-box from Sierra for a more reasonable price than OEM. Are Sierra parts good quality or Do you guys think that OEM should be the way to go?

 

[Laddies]

Re: Merc 20hp 200 issues

CDI are the best, but if you get a discount at a auto parts store they are availabe at NAPA and most other major chains from Sierra and they are better quality than OEM at lest I will use most anyones before mercs