QuestionHave a 48" mower that sputtered a little while mowing so I cut it off and now it won't start back up. It will turn over but just won't fire off. I tried and tried until battered was bout drained. Hooked truck up to battery and tried spraying a little ether in the carberator but still won't fire. Oil is good and it has gas what do you think?
AnswerJeff
You probably have to remove the carburetor and clean/rebuild it.
Condition of gasoline: Old or contaminated gas will make any engine harder to start. If the problem is with an engine using last year's gas, drain the old gas completely and dry out the residue in the fuel tank if possible. If debris or water is found in the old gas, the carburetor may need to be drained and cleaned as well. Then add fresh gas (not from the batch sitting in the can since last year!). In cold weather, the water can turn to ice inside the carburetor float bowl casusing all sorts of problems including flooding of the engine.
Obviously, the engine won't run without gas!
Is there some in the fuel tank? If it is near the bottom, add enough so that there is no doubt about there being enough to reach the outlet pipe regardless of any slant on which the lawn mower is located.
Make sure any shutoff valve is open.
Check for a clogged fuel filter, if there is one. There may be a sediment catching screen at the bottom of the tank as well.
If your engine uses a primer bulb, does it feel like it is doing something? There is a distinctly different feel when it is actually squirting a little gas into the intake pipe. Check that the rubber hasn't deteriorated but if many pushes still doesn't do anything (and you're sure there is gas in the tank and the engine hasn't flooded from TOO MUCH gas), the carburetor and/or fuel line may need cleaning.
If you are using gas from last season, discard it and start fresh. While old gas will usually work in an engine in good condition, this is not always the case, especially with one that has seen better days. The more volatile fractions evaporate leaving behind higher flash point gas. Why add another unknown factor to the puzzle?
There may be water in the gas. If the carburetor has a drain plug, operate it to rid it of the bottom layer which would have the water. If there is no drain, repeated pulling on the starter cord should eventually clear any reasonable amount of water.
Once you have exhausted these obvious problems, determine if gas is reaching the cylinder as follows: Perform the normal starting sequence and then, assuming it shows no signs of wanting to start, immediately remove the spark plug. If fuel is reaching the cylinder, the spark plug should be damp with gas and there should be a very distinct odor of gas from the spark plug hole. If there is none, then there could still be a blockage in the fuel line or the carburetor may need cleaning.
A flooded engine, most likely due to extended unsuccessful attempts at starting or a defective carburetor (float valve stuck open or gas-logged float) will result in inability to start as well and a distinct odor of gas. You might find raw gas coming our of various orifices - air filter as well as exhaust. (Note that in severe cases, enough gas gets mixed in with the oil to significantly increase the level in the crankcase and reduce the effectiveness of the oil. This will require an oil change.
