2000 Merc 200 plugs wet fouling

[Brian Robertson]

2000 Merc 200 Saltwater standard carbureted V6 2 cycle Ser. OT104120 Mod. 1200425WD purchased used - don't know much of history - - all plugs wet fouling but seems to run OK - - idle was high(1100)so I checked all adjustments (seemed OK) and found idle-timing screw vibrated out so I adjusted to 650rpm and tightened lock nut - - was getting blue smoke - saw that oil pump link adjusted high so I adjusted to align lines - minimal smoke now - - book calls for BPZ8HS10 plugs but engine has BPZ8HN10 - don't know how much difference this might cause - - don't see black smoke in exhaust but there is black residue inside prop and shaft - also odor of partial burn fuel - - have SELOC book but not finding much help there (just not clear on what they mean) - think I may need to adjust fuel idle mix but not sure how on this engine - has 3 two barrel carbs - assume one barrel for each cylinder - I think the adjustment is the one with the plastic slotted cap that restricts how much adjustment can be done but not totally sure - does plastic cap come off to adjust? - one adjustment on either side of each carb - is there a sequence to adjusting? Engine seems to run fine but a little rough at idle though I think this may be normal with these engines I am not sure - - even after running at higher speed for some time the plugs still come out wet - any help greatly appreciated

 

[gss036]

Re: 2000 Merc 200 plugs wet fouling

I have an 89 Merc 200 w/carbs. I think the carbs have a low speed and a high speed jet and they are not adjustable except changing to different sizes. I am not a mechanic so I could be wrong.<br />I think I would try to decarbon the engine with a strong shot of Seafoam, 1 pt can, 3 oz TCW3 oil and 3/4 gal gas, use a small tank to mix. Run for about 15 minutes,let sit for about an hour, then do it again. You should get lot of black crud from the exhaust. Check/change plugs and see how it runs.

 

[MACSOUT]

Re: 2000 Merc 200 plugs wet fouling

Gss is right, due to you not knowing the history, decarb first. Sounds like someone has tampered with the adjustments. We also need a little updated history to assist you. Are you getting full throttle? What are some of your problems besides wet plugs? Wet plugs are somewhat normal. Plugs are wet after first shut down due to when you shut your ignition off, your engine still turns over several revolutions before shutting down, the carbs don't. so you will see fuel on the plugs after shutdown. And yes, the plastic covers do come off of the idle jets (pry gently). Screw all jets in (clockwise) until they seat gently. Back out counter clockwise 1&3/4 turns (rule of thumb) adjust from there. doesn't sound like you have much of a problem

 

[Brian Robertson]

Re: 2000 Merc 200 plugs wet fouling

Thanks for your replies and suggestions. The engine and boat seem to operate very well. On test runs I go to WOT and play around with the trim in the calmest water I can find and get between about 5100 and 5400rpm - top speed so far according to GPS is 43 knots - Pro-Line 20 Walk - Normally we cruise between 3600 and 3800rpm at about 23 knots in calm seas - but we don't see a lot of calm seas here so often have to run at lower rpms. My concerns began with the blue smoke and that some things appear to be out of adjustment. Also noticed the black soot inside prop and shaft housing as well as what I call the odor of partially burned fuel. But that may be the gas we get here - I also notice a lot of black in exhaust pipes of cars here that I don't recall seeing in the states - some here think our fuel is not always unleaded - sometimes a pink tint is noticable. I keep checking the plugs to see if they look like what the experts say they should look like and they are always wet - not sure if this is gas or oil - but they don't appear to be carbon fouled nor do I see any of the other problem conditions plugs can sometimes show. We live on a small island off the east coast of PR and have no mechanics so I have to try to figure this stuff out on my own or take the boat over to a marina in PR. Just trying to learn how to keep this thing in the best condition with the fewest problems so we done have a breakdown out here - we boat around the islands east of PR and to US and British Virgins - not a good place to have the engine quit. Thanks again for all the help and I sure would be interested in hearing any more thoughts and ideas. The decarbon thing is a new one on me so I have done a lot more research on the subject and will be trying to find products to remedy this situation and keep up with doing this with all the other regular maintenance stuff. We get to boat 12 months a year (80 degree air and 80 degree water year round) here and often go out a couple of times per week so we have to put more time into maintenance than most.