Outdoor Power Equipment and Small Engines - Lawnmower clicks - won't start - water in gas

I recently purchased a Yardman riding mower that is about a year old. It has a Briggs and Stratton 17.5hp engine. Everything worked great for a couple of days. I filled the tank up with gas and let it sit for a week or so. I tried to start it again and it had a difficult time but finally started. It ran and died and ran and died until it finally wouldn't work at all. I realized that there was probably water in the gas so I purchased some HEET. I tried to start it and it only clicked. I thought the battery may be dead so I had it checked and bought a new one. I still only got a clicking sound with a fully charged battery. Does anyone know what I should try next? Do I need a new starter now? Could there still be water somewhere preventing it from starting?

Thanks for your help.

Do you have a voltmeter or 12v test light? If so, check for voltage at the starter terminal while trying to satrt it (when you hear the click). If there is none, the solenoid is bad.

Something to add to what Cheese said...
Be sure to clean all connections. While sitting idle wires corrode where they connect to the crimped part of the connectors. Check all screws for tightness.
Another quick way to check the solenoid is to cross the two posts on it with a screwdriver.
If the engine starts, then everything else is ok, replace the solenoid. If it doesn't turn over or start, keep looking for a bad connector.

Good luck,

The lawnmower turns over now and will run. All I did was replace the spark plug. Although it is still having problems. It is back to runing and coming close to dieing and then running full speed and so on. During the time when it almost dies - white smoke blows out and black stuff is dripping out the bottom. Any ideas on what is happening?

It sounds like you have carb problems. This will cause the surging you describe. Check the oil in the crankcase. Does it smell like fuel?? Is it over full & thin. You may need a carb overhaul (with a new float). If it's a carb that is above the intake valves, it may have been "hydrolocked" with fuel, causing the no crank condition. Also check the fuelpump for a leaking diaphram if so equipped. If you have fuel in the oil, do not run it!! Fix the cause & change the oil first. Let us know what you find,, Roger

I agree, you have carb problems and fuel in the oil. Don't run it anymore until it is fixed, or premature engine damage will result.

Clean the carb out and replace the needle at the least. Then when you have verified that the leak is stopped, drain the contaminated oil and refill with new oil.