My engine starts up but will rev up and down(surging), when I try to go over an area of grass it eventually shuts off. I have changed oil, changed spark plug, and changed the air filter. The smoke coming out of the exhaust is black when it is reved up, which makes me think it is fuel related. What could this problem be, I have been told water in the gas, but is there anything else it could be?
Also, there is a triangle looking white piece of plastic that is right next to the carburetor above the gas tank that has a spring coming off of it, I took the spring off on accident and the triangle pieced moved around, now I don't know exactly how to put it back together, it seemed fairly self explanatory, but I am second guessing how I put it back together, does anyone have a picture or diagram to show how that should be put back together?
I replaced the diaphram and it seems to be running a lot better. It still surges a little bit when the gas tank is filled up. Once the gas gets a little lower it runs much better. I can finally cut my grass again!