Cleaning the fuel float bowl
Note: this procedure will often cure no start issues and or surging issues, or once done a little running after the fact will clear up surging issues as well.
Often gas with ethanol will cause gunk build up in the float bowl making your mower run badly and have a 'surging' behavior especially at low idle speeds, or cause it to not run at all (almost all gas has ethanol as an additive now for 'emission' reasons so assume you have it unless you KNOW you don't). This can take as little as a few weeks or a month or two of not running to happen. Frequently a simple float bowl and carb cleaning will resolve these issues completely or at least to get you back to a running point.
To clean the float bowl area, it's best to remove the carb. (make sure you pinch off gas lines with a vice grip or similar to keep it from spilling out and remove things carefully to avoid breaking seals on the intake)
Tip the carb over a catch basin or oil drip pan and turn it this way and that to pour as much excess fuel as you can. If your carb has a electric solenoid or an overflow screw on the bottom, removing this will let you pour fuel out of the bowl area.
To begin cleaning, Turn the carb upside down. Typically there are 2 or 3 screws that hold the bowl to the bottom of the carb. Do ALL of this over a nice metal tray that will catch any falling parts like small screws, carb jets, springs, plungers, etc.
Very carefully undo these screws and work the bowl until it breaks free of the seal
gently pull the bowl off the bottom of the carb. and you should see the float mechanism and main jet sticking out toward you. This visible area, all the orifices, and the bowl you removed are what you want to clean.
ANY orangish discoloration, sediment, or other gunk that is not obvious parts of the carb is bad news.. or good news because you're about to remove it and you found a problem that was worth fixing. If everything is clean, shiny, and aluminum and plastic looking, all is well in there, put it back together and move on to other DIY projects. :)
To clean it out assuming you saw at least a little orangish discoloration, a good pressurized can of carb cleaning spray is GREAT... HOWEVER, do not let carb cleaning spray get on ANY gaskets or rubber seals. The chemicals in carb cleaner will expand the rubber and make the seals not fit properly anymore and ruin them. (beware there is a TINY, impossible to see rubber seal on the plunger for the float so you MUST REMOVE THE FLOAT if you want to use carb spray to spray the metal on the carb or the jets while they are still on the carb. It may be better to just use a little gas in a metal tray and a soft toothbrush to scrub things off and clean them out. Typically it's just a pin you have to slide out in order to remove the float and plunger, it's sometimes a little tricky getting it back in just right.
You can also use your air compressor spray tool to blow out passages and dry out parts you are cleaning and it's great to blow out all the orifices you see in both directions ... BUT ... watch out because it is easy to accidentally blow out the jets and lose them! Also, wear eye protection ... seriously, do it, even if you're not using compressed air.
Once you have cleaned everything, make sure no little parts are in that handy metal tray you worked over the whole time. If there are any, find where they belong and put them back. Nothing in there is unnecessary... nothing!
Once you put it all back together, the carb will naturally refill with fuel and you should be able to start right up after a few seconds of cranking.
Any residual surging will often clear up after some run time, I like to use a little mix in gas carb cleaner after doing a carb cleaning. If my tractor has sat more than 2 months not running, I often check this before even trying to start to make sure I don't pull any gunk that did build up into the jets and clog them. Cleaning the bowl is easier than cleaning the orifices!
on Nov 15, 2013 | Garden