Riding mower won't start - stumped

[Joe Pelonio]

While I have done a lot of my own repairs on cars and small engines for many years this one has me stumped. I have a Sears riding mower, model 502.255070, with 10 HP Tecumseh electric start. Last weekend it ran just fine. Today it cranks well (until I ran out the battery) but will not fire even a little.

The gas is full, oil fresh and full, the fuel shutoff is on, there is gas in the bowl, and good spark. The fuse is good, and I had it in neutral, mow lever off, and was sitting on the seat. When I pull the plug, it smells of gas and looks wet. I held the plug to ground and had my wife crank it and got a nice spark (and shock). I turned it over 10 seconds with the plug out to help dry it out in case it was flooded. I haven't tested the compression yet because I have to find my gauge and we're off to the baseball game soon, but it seems fine by the slower speed with the plug in. Are there any other safety sensors/switches that I may have missed, or any other ideas?

[Harold Burrell]

What does it have as far a choke and throttle? Are they "automatic" or manual?

[Justin Ludwig]

You need fire, air and fuel. Sounds like you ruled out fire and fuel. Check to make sure the choke isn't stuck and then try starting with the air filter assembly removed.

[Bill Orbine]

If you have spark, safety switches isn't the problem. You might have fouled the plug....replace it.

[Duane Meadows]

Compression or timing? Sheared flywheel key can let timing change. Would as Bill suggested try a new plug first.

[Todd Willhoit]

If it isn't timing, how about water in the fuel?

[Joe Pelonio]

You need fire, air and fuel. Sounds like you ruled out fire and fuel. Check to make sure the choke isn't stuck and then try starting with the air filter assembly removed.

It's a manual choke, actually just the throttle all the way up. That could be a possibility, perhaps the choke cable fell off on the carburetor end and it's stuck closed. I did try it with the air filter off but I'll have to remove the whole assembly to check the choke. I can't imaging how water could be in the fuel. I filled it before mowing last weekend and it's still 3/4 full. If it's not
a problem with the choke I'll check the compression. I can't find spec, probably 75-100 lbs? Hopefully I'll get time tomorrow to work on it, it's our anniversary but we celebrated today with the kids and grandson at the
Mariners/A's game (we lost). 10615594_628476638611_6266042925315564896_n.jpg

[Jerome Stanek]

try a new plug some times they will not fire under compression

[Steve Rozmiarek]

Did it run fine before, or any issues you noticed last time you ran it?

[Joe Pelonio]

It ran great last weekend, and just sat in my shed since.

[ray hampton]

I own a craftman riding mower that would quit because the gas cap gasket was bad, I own a self-propel mower [walk behind ] before that would require the cover over the flywheel remove so that two screws holding the intake manifold COULD be tighten down every time that I went to mow the glass

[Joe Pelonio]

I own a craftman riding mower that would quit because the gas cap gasket was bad, I own a self-propel mower [walk behind ] before that would require the cover over the flywheel remove so that two screws holding the intake manifold COULD be tighten down every time that I went to mow the glass

The gas cap gasket looks OK but it does normally run without the gas cap on (don't ask). I'm on the way to get a new spark plug in a few minutes and try that before taking it apart. The nearest place is 20 minutes away so it will be a while.

[Tom M King]

How old is it? The more worn the motor gets, the harder they are too start. If it has some age on it, a compression test would be the first thing I'd do. It goes the same with big diesel tractors too but "harder" to check the compression on. I gave away a 15 year old riding mower a couple of years ago for scrap, and after 30 years on the big JD, had the motor rebuilt. It's unbelievable how quickly the tractor starts after I had the motor rebuilt. I had been nursing it, and coaxing it to start for several years. The old riding mower finally drew a line that I didn't want to bother to cross, and it had cut grass just fine the previous week.

[Joe Pelonio]

The lawn is mowed!

I put in the new plug and got one pop, then nothing. I removed the air filter assembly (2 screws) and saw that the choke was closed all the way despite the throttle being well away from the choke position. Moving the lever all the way up and down did nothing. I opened the butterfly with my finger and found that it was hitting and getting stuck on the edge of the bore. Working it many times with a little WD40 at the top and bottom I got it to where it moves freely now. I put it back together, started it up and I'm glad I replaced the plug because it's running much better now, starts within seconds. Thanks to all for your help!

[George Bokros]

Glad you got it fixed. The choke being stuck likely flooded the engine and unleaded gas can foul plus to the extent that they need to be replaced. I experienced this with a car some years ago. So good thing you replaced the plug to be sure.