Not "turning over" is you turn the key to start positon and nothing, or only a brief click sound happens. Nothing more. no rrrr rrrrr rrrrr rrrr from the starter motor. "Turnover": you turn the key to start position and the engine goes : rrruhr rruhr ruhr ruhr as the starter motor rotates the flywheel and thus the crankshaft and the engine "turns", this is also called "cranking", it may or may not "start"when it goes vroooom and maintains a long vrooooooooooooom and "runs" which is when it runs. But it may "fire" when it tries to run--this is also "combustion") and then the engine may run in some fashion: it may splutter, or vibrate, or chug chug chug, or plooga plooga plooga, or p-ka, p-ka, pka: or it may "run" smoothly, or run in any of the aforemention sound versions, and then stop running (die-quit-stop= silence). When "turning over" rrrrrr rrrrr rerrrrrr, but not yet "running" (vroooooooooom) it may momentarily seem to "run", or may spit back (pip pip !!) or it may backfire (blam !) . That is not running, it is "turning over" and is "firing". "Firing" is not yet "running". It can fire on 1 to 8 cylinders and any number in between, and "run", but not operate smoothly. (vrooooooooooom) "Running" is not yet operating normally and smoothly, coming to operating temp, choke coming off and rpm slowing to a smooth and normal idle rpm (which is not the chugga chugga chugga) , for which: Air, fuel, spark: each in the right amount, at the right time. Chuga chugfa chugfa is not normal, backfire blam !) and spitting back (pip pip pip) is not normal, black-blue-white exhaust AFTER first start and run is not normal. RRRR, RRRR , RRRR from the stater crankng but no firing, and thus no start is not normal. Clakety Clakeyt bang bang clakety is not a normal sound, nor is ting ting ting ting, or rrrr rrrrr rrrrrr BOOM. Electrical smelling smoke, or orange-yellow-red flames are not normal. As to the specific question..from description, it sounds like it is flooded from too much gas (smell gas, black exhaust--runs good (vrooooom) once running. Try a start assuming flooded from first try---pump twice, hold gas pedal to floor and crank (rrrrr rrrrrr rrrrrr rrrrr) for quite a while and see if you get a start (vroooooooom). it may take two to three long tries...if it starts you have proven flooding is the issue--then have to find out why the flooding, as others have suggested. Hope that helps.
Nico
