50HP Johnson rough idle fouls plugs

[homerparrot]

I have twin 50s on my aquasport and one idles perfect, but the other is supper rough and sometimes stalls and seems to be missing often. The hole engine will shake all over. The top spark plug seems to be fouling. The engine also boggs when the throttle is opened up quickly, then evens out and accelerates. It seems like is is running too rich and sort of flooding the motor when accelerated. Both fuel bulbs feel full. Both tanks fed of same 50 gal tank, one line to h20 seperator then split to each engine. <br /><br />Any advice on fixing this problem? Are these carbs adjustable? How?<br /><br />thanks<br />tony

 

[voodoo]

Re: 50HP Johnson rough idle fouls plugs

What year ? Compression? Last carb rebuild? New plugs?

 

[phatmanmike]

Re: 50HP Johnson rough idle fouls plugs

VOODOO has goo dpoints.. you need to check the compression of each cylinder on each engine. what do the other(good) plugs look like. <br /><br />i had a 50hp evinrude, 1980, that would do exactly as you describe. problem was it wasnt rich, it was lean on that cylinder, and lost compression, and would only run on one cylinder, hence the abnormal shaking. youll be surprised how well these big twins run on only one cylinder.<br /><br />eventually the engine puked the #1cylinder, the bad cylinder, it puked the rod all over the back of my boat, im now getting a new powerhead

 

[homerparrot]

Re: 50HP Johnson rough idle fouls plugs

Year- 89, It was a VRO, but that crapped out and blew the powerhead, so when we rebuilt we junked the VRO and we now mix our own fuel.<br /><br />Compression is strong and even. It has fresh plugs. I will compare plug to plug when I go to the dock tommarrow. <br /><br />I think it has been a while since last carb rebuild. <br /><br />We did have some problems with water in the fuel about a month ago. I pumped the tank as much as possible and added water remover then re filled. Once all the crappy fuel ran threw and many fouled plugs later it was running fine. <br /><br />Another thing that could be a part? The motor was getting hot about a month ago, so I talked to my mechanic about it and he recomended pulling the thermostate. I did this and it now runs cool. I plan on replacing the thermostat after fishing season with a new one. Currently no thermostat in place.<br /><br />Anyone see anything that could be an issue, or have any advice on what to look for. I thought it was running super rich because it would fowl the plug and bog when reved hard? <br /><br />Anything helps<br /><br />thanks<br />tony

 

[tonyscj5]

Re: 50HP Johnson rough idle fouls plugs

I ran the motor agian today, same results. The upper plug is supper greasy and wet, black liquid crawling up the threads. Today when I would throttle up from idle to mid throttle, the engine would just kind of sputter then suratically rev up to speed. What should I do to figure this out? I am thinking of just tairing down the carb, cleaning inspecting and replacing.<br /><br />What do you think, any one have a better idea? I just dont want to do that if it will do no good.<br /><br /><br />Thanks<br />Tony

 

[phatmanmike]

Re: 50HP Johnson rough idle fouls plugs

tearing down and cleaning a carb is NEVER a bad thing, especially on a 2stroke!!! if you carb craps out, you get no oil.....etc etc etc bad stuff<br /><br />if these are new to you, then is definately a good thing to tear apart the carbs and get the rebuild kits.<br /><br />same carbs as on my two 50's(but diff years)<br /><br />REALL EASY. I THINK ITS JUST A NEEDLE/SEAT and a few gaskets. very minor stuff<br /><br />id rather do it and have it done, knowing that its done right.<br /><br />just a note... without your thermostat, your engine performance will suffer and you will get a rough idle and week acceleration. replace the thermostat. its there for a reason. without it, your motor will never get up to operating temp, since it always has a fresh / new supplie of water for cooling, if this were a car with a closed system , it would be different<br /><br />m ikey

 

[tonyscj5]

Re: 50HP Johnson rough idle fouls plugs

Okay I took the carb off of the cyl that was fouling the plug and replaced it with a carb from a parts motor I have(the guy I got it from said the motor ran fine, just the lower unit screwed up bad). When I put it back together after forgetting to connect the plug wire, if fired up and idled fine. I was excited and took it out into the bay. When I took it above idle with a load on it, the engine just craped out. It did the same thing as before, when I gave it full throttle the engine would surge as it reved up. Reving up, then crapping out, then reving up more, then would crap out then rev up??????? WHat the heck is going on. The I tried replacing the bottom carb with the other spare and inspected the reeds which looked fine. I put it back together and not much change. I didn't have a chance to take it up, but it wasn't running smoothly at all. When I tried to rev it up, the motor would sputter, like it was being flooded??????????<br /><br />What now? One thing I noticed when it got dark was the spark was arcing from the boot to the head. So I replaced the plug, did not do the trick. I am out of ideas?<br /><br />I figure it could be an electrical issue, not getting enough spark? WHat should I do? What should I check? How do I test the electrical? If that could be a problem. <br /><br />The salmon fishing is red hot and I am stuck at the dock! Please help.<br /><br />Tony

 

[tonyscj5]

Re: 50HP Johnson rough idle fouls plugs

Could it be the thermostate being removed? I am just looking for a place to start, I thikn I have ruled out the carbs and reeds, and since one cyl runs fine I think the fuel pump must be fine. If not the thermostate I am leaning toward the ignition sys.<br /><br />Could one of the experts please chime in here, I need some direction. I have trip planned to take some friends fishing tommarrow and dont want to have to cancel.<br /><br />Please Help<br /><br />Tony

 

[tonyscj5]

Re: 50HP Johnson rough idle fouls plugs

also to avoid confusion uyF5C9 and tonyscj5 are both me.