98 Mercury 50 hp Oil Injected

Hey guys,

I just bought a used 1998 50hp oil injected mercury with very few hours on it. The problem is that the guy I got it from has let it set up for about 4 years with old gas. I cleaned the old gas out of the tank and lines and added fresh gas with some Seafoam. The motor will fire right off but it burns the gas out from the choking then slowly dies out. It will run forever if I keep hitting the choke. I don't want to risk putting it in the water and trying to run it. It might would clean some of the crud out but it might leave me somewhere also.

Are there any recommendations short of pulling the 3 carbs and cleaning them individually?

Thanks

Re: 98 Mercury 50 hp Oil Injected

Don't mess around with "other" fixes. Pull the carbs and clean them properly. These carbs are very simple, and the kits are relatively inexpensive. Don't risk damaging a great little motor from running a lean cylinder. Well worth doing it right. Good luck.

Re: 98 Mercury 50 hp Oil Injected

Ok,

I pulled all 3 carbs today and completely disassembled them. Over all, they were in good shape. The biggest problem was shelac plugging the metering valves. I cleaned all of the air/gas venturis with pipe cleaners, removed all the shellac, put new gasket kits etc. in all 3 and remounted. The engine will fire right off now before you can release the key. My only issue now is that I cannot get the motor to idle as low as it should without adjusting the idle air mixture screws. I was careful to count the turns I moved them from the original adjustment just so I could remove the varnish from the tips of the screws. All three carbs have the same settings. Each carb only has this one screw and there are no other adjustments on the carbs. I'm not familiar with hearing 3 cylinder engines run so I don't know how it should sound. It also seems to me that it might be a little rich on the oiling.(Injected). I cannot find a set/stop linkage screw on any of the carb linkages. There is the governor adjustment and the throttle cable stop screws but I cannot slow the engine down anymore with them. I would describe the idle speed as having the high idle lever raised a bit but it isn't. Any help would be appreciated. I am certain the carbs are perfect in so far as them being clean and assembled correctly.

Thanks

Re: 98 Mercury 50 hp Oil Injected

Sounds like you got the carbs cleaned up correctly. Did you put gasket kits in the carbs when they were apart? The round gasket that goes over the main nozzle usually does not survive disassembly. The high idle sounds like the carbs now need to syncronized. Port side of motor there is a link rod that connect all three carb butterflies together. You'll notice on each carb cam, there is a phillips head screw. The middle one has a roller cam attached for throttle pickup. The easiest way to set this if you are inexperienced, is to do so with the airbox off so you an see the throttle plates. Loosen all three screws. Make sure the butterfly on the top and middle carb are completely closed. Usually a little finger pressure on the butterfly cam will ensure this. Once top and middle are completely closed, tighten TOP screw. Do, not tighten middle screw yet. Next do the same as above with the bottom carb butterfly. Once you are sure all three are closed, you can now set the throttle pickup cam. Move the roller towards the plastic cam. There is a line through the center of the roller axis, that when correctly adjusted, will line up with a line on the cam itself. Tighten middle screw. Idle mixture screws should be set at 1 1/4 turns out from lightly seated position. As long as you haven't messed around with all the other timing arms and throttle stops too much, the carbs are clean, the syncronizing has been done completely, this engine shouldn't need much more adjustment than a 1/4 turn in or out of the mixture screws, to make this thing purr. As I said before, this is a great little motor with nice idling qualities for a two stroke. Good luck!!

Re: 98 Mercury 50 hp Oil Injected

Thanks a million! I'll give this a shot tomorrow. I did replace theose gaskets while I had the carbs torn down.

Re: 98 Mercury 50 hp Oil Injected

SXMERC,

I synced the carbs per your instructions and I think I have the middle carb with the roller lined up properly with the cam line. My cam has a mark right along the bottom which is the one that would line up with the roller in a closed throttle position and then there is another mark about an inch and a half higher that would not line up without advancing the throttle. The adjustment seemed to help for the most part and I played with the idle air adjustment and settled for setting them all at 1 and 1/2 turns from bottoming out. I think the idle speed is probably about right now but it still does not idle or run as smoothly as I think it should. I'm headed to get 3 new plugs as the ones in the motor have set up for 4 years and appear to be older than that. I'm also replacing the thermostat. I put a brand new water pump in it yesterday and have great water flow. The motor has very low hours on it, less than 50 in fact. It appears to be oiling just fine and am getting no beeping or other low oil indicators. i purged the fuel line and bulb before connecting the line yesterday and replaced the fuel/water/ seperator filter. I will replace the in line fuel filter on the motor today as well. Do you have any other suggestions?

Re: 98 Mercury 50 hp Oil Injected

Looks like you are pretty close to perfect, by what I can see in your picture. The only other thing I would do seeing as it sat for 4 years, is to rebuild the fuel pump. Diaphragm kit runs about $20 and is very easy to do. Pretty good chance that there is some deterioration to those diaphragms. Lastly, if you are able, back this thing down the ramp at your closest ramp for final adjustment. I find it's the easiest way to get them set perfect. A little backpressure on the exhaust makes a big difference. Good luck!

Re: 98 Mercury 50 hp Oil Injected

Thanks,

Took it to the river today and burned about 3 gallons of gas. Ran perfectly at all speeds! Thanks again!