Cleaning carbs

ezzriderezzrider Posts: 79 Greenhorn
I have a 1994 115 Yamaha on the back of my pontoon boat. The motor is running rough and will not keep any idle unless I use the choke and even then runs rough. I believe the issue is with the carbs. I have used carb cleaning spray and Sea Foam but still have problem. Is there a way to properly clean carbs without removing them from the motor? Due to the location of my motor on the back of the pontoon boat there is almost no room to get in front of the motor and it is going to be a real pain to take them off of the motor.


  • DunkDunk Posts: 107 Officer
    Get ready for the pain in the butt. They do need to come off to clean them right. Anything you spray into the throats just going down the throats and doesn't get to the jets.
    Marine Surveyor
  • ChuddybuckrivetChuddybuckrivet Posts: 3,156 Officer
    Dunk wrote: »
    Get ready for the pain in the butt. They do need to come off to clean them right. Anything you spray into the throats just going down the throats and doesn't get to the jets.

    ^ this
  • ezzriderezzrider Posts: 79 Greenhorn
    Dunk wrote: »
    Get ready for the pain in the butt. They do need to come off to clean them right. Anything you spray into the throats just going down the throats and doesn't get to the jets.

    I sort of came to that conclusion late yesterday afternoon. Oh well. Thanks for the input.
  • MenziesMenzies Posts: 19,289 AG
    I would go further and say that you should NEVER clean them while on the engine. all you are doing is spraying the crap into your engine.
    Maybe if we tell people that the brain is an App, they will start using it.
  • flatsjunkie88flatsjunkie88 Posts: 1,364 Officer
    Give this a shot

    dunk's decarbon method:

    This works for Carbed, EFI, Ficht, HPDI, Optimax and even 4 strokes...
    First you need a separate small fuel tank. One of those 3 gal red Tempos works great or an empty gal milk jug will also work, but might be a bit messier..

    I use Seafoam over the OEM stuff like OMC Engine Tuner or Merc Power Tune because in the last few years they changed the formula and you have to let them sit up 12 hours. Who's got time for that?? Seafoam you can buy from NAPA, CarQuest or other auto stores. Seafoam works in 15 mins.

    You'll need 3/4 gal of gasoline and one 16oz can of seafoam for each engine. Don't forget to add 3oz of oil if you are premixing in a carbed engine. Use about 3 ft piece of fuel hose off the little tank. You connect this tank to your engine by pulling off the main tank fuel hose off the intake side of your water separating fuel filter and plug the hose off the small tank on to that fitting. Or you can separate the fuel line on the tank side primer ball, so you can still use your primer. If you have an engine that has fuel plug then you need a fuel plug on the little tanks hose.

    Start the engine, let it warm up and start pulling the mix into the engine. You may have to increase the idle to keep it running once she get loaded with the Seafoam. Run the engine 15 mins in the dock or just cruising around under 2500. Then shut it down and let it sit for 15 mins. Restart the engine, the smoke you see is the carbon burning off. Do the whole thing again and let her sit again for 15 mins. If she smokes after the second time do it again, but I've never seen one still smoke after three doses. The gallon mix should be enough to do this 3 times. You don't need any wide open throttle, you don't need to change the plugs. If it's cleaning the combustion chambers it's also cleaning the plugs, but every 50-60hrs is good time to change plugs in most engines.

    I cleaned a antique evinrude one time that had a 1/4" of solid carbon on the exhaust chamber walls by running a 1/2 gal of the mix through it. Seafoam has been around since the 30's and it's what they used when they were burning straight 4 stroke 40SAE oils in outboards.

    You guys with the 4 strokes think you are immune from this? Those engines work 10 times as hard as any auto engine ever will and they will carbon up. I bought a Bronco two years ago that had 95,000 miles on it. When I used seafoam on it I had the neighbors hanging out of their front doors looking for where the fire was after I started it the first time there so much smoke.

    Too many are under the assumption that it's totally the 2 stroke oil that causes the carbon, Wrong... it's also the additives they put in the fuels today. The carbon inhibitors in 2 stroke oil are there for this reason also. Remember when gasoline used to smell like gasoline, today it smells more like bad cologne.

    For those guys that like to do the carbon treatment by spraying it down the carbs Seafoam also comes in spray can called Deep Creep. It's the same stuff under pressure. Says right on the can Oxygen Sensor Safe, for you Yam guys.

    After that if your engine maunf recommends a daily additive treatment then do that in the mean time, but all 2 stroke outboard need decarboned every 50-60hrs. If I owned a 4 stroke I would do it the same. Once you are set up with the tank and hose the Seafoam is only 5-6 bucks can. It to easy not to do it
  • EggsuckindogEggsuckindog Posts: 1,528 Officer
    Heres an idea - pull the bowl drain plugs and squeeze the bulb - that will at least flush the bowls - next locate the low speed idle jet screw ( hope it has one) - turn slowly inward and count the turns. The remove it, use some ballyhoo copper wire or a mono that will fit. That is actually an air jet, replace and again turn all the way in and count the turns back out to get where you were.

    Dunk does this make any sense since access is so tough?? that is most of a carb clean except the gaskets and a new needle and seat. Speaking of which, pull the air box and start it, look in the carbs to make sure one is not overflowing, that would be a needle and seat issue.

    flatsjunkie - the decarb is not a carb cleaning method, or Dunk would have mentioned it. It does nothing for carbs as your just spraying it down the throat of the carb, not the passages.
    1976 SeaCraft master Angler - Merc 200 XRi
  • screamin seamanscreamin seaman Posts: 1,492 Officer
    To do it right pull the carbs!!!

    But another thing to try (if it's just some varnish and not trash plugging the passages) is some carb cleaner that Yamaha makes. I can't remember the name, will look at home tomorow, it's some nasty stuff but is safe for rubber parts. Mix 50/50 with fuel and fill the float bowls with it. Turn engine over a few turns to pull through the orafices and then let sit. Drain it a few hours later, prime engine with good gas and see how she runs.
  • EggsuckindogEggsuckindog Posts: 1,528 Officer
    I doubt he has a varnish issue, sounds like he uses it
    1976 SeaCraft master Angler - Merc 200 XRi
  • ChuddybuckrivetChuddybuckrivet Posts: 3,156 Officer
    I think Eggs suggestion would be a good idea before pulling the whole carbs, cause for one, it wont hurt. And it's possible some gunk in the bowl could be causing the problem.
    That being said, if it's anything like the carbs on my small Yami(50hp), there are other jets, passages, etc that clog easily, and if that's the case, you'll need to pull the carbs.
  • BillatstarbriteBillatstarbrite Posts: 520 Officer
    Dump two 8 oz bottles of Star Tron into the fuel tank and run the engine.
  • ezzriderezzrider Posts: 79 Greenhorn
    Decided to pull the carbs and ordered a rebuild kit for the two carbs. Going the pain in the butt way.
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