Kubota T1670 Turns Over But Won't Start

[sumpnfishy]

Been messing with this for several days and running out of ideas so any help more than welcome.
Have mowed a few times this year already with no problems using leftover gas with stabilizer. The other day mowed for about 20 minutes and then suddenly mower stutters and shuts off with no warning. Usually when I run out of gas I get a few stutters & gasps and then 10 feet later it finally stops. This time it was stutter/done. Turns over just fine but won't fire. So I drag it to the garage and check fuel to carb after adding fresh gas and see it's getting fuel. Pull sparkplug and turn over and see it sparking just fine. I splashed some fuel in carb and nothing. I even see fuel spitting out the exhaust so I think it's getting plenty of fuel.

So it turns over, gets fuel, is sparking but other wise nothing. Doesn't even try to fire. I know if the safety switches fail it wouldn't turn over. Talked to local repair shop they didn't have any ideas and of course this time of year looking at a couple of weeks before they could look at it. I even tried starting without the gas cap to make sure the air intake valve wasn't clogged (getting desperate).

I'm starting to think it's something major but as I turn it over nothing sounds unusual in the engine like a busted piston. Just no fire.

Starting to shop for a new mower but just wanted to post here to see if there might be something simple I'm missing.
Thanks!
Dennis

 

[North Idaho Wolfman]

Pull the spark plug and do a compression check.

 

[redfernclan]

May have died because of a fuel problem and then you fouled the plug. Put in a new plug and give it a squirt of starting fluid. if it tries to start, you have good compression and the ignition is fine. You are looking at a fuel problem. If it doesen't even snort with a new plug and starting fluid, you have an ignition problem.

 

[rentthis]

You said that you are getting spark so that eliminates that and safety switches. Timing is seldom the problem. If you do as redfernclan suggest using starting fluid, I use carb/choke spray, it should fire if it has compression. If it fires and shuts down when it burns off the spray and will continue running with the spray, remove the bowl at the bottom of the carb and check for water, dirt, bad fuel etc. while you are in the carb, clean the jet. If you remove the jet and can see through it, clean it anyway. The least bit if varnish from old fuel will keep it from running right or at all. I use the wire out of a bread tie to clean them.

 

[sumpnfishy]

Thanks for the reply's!

Ironically my can of carb cleaner won't spray very well (lot of things breaking on me lately) but I did manage to dribble a fair amount into the carb, and still no fire. The guy at the shop said if I can see spark the plug should at least cause the engine to attempt to fire. So he didn't think that would be it.

Not sure of a good way to check compression without a checker. But if that is indeed the problem then I'm looking at an expensive repair for sure. With the plug out it was spraying fuel out the hole when I turned it over. But I know the ring could still be cracked. I guess if it suddenly broke it would explain everything. Never had that happen before so I'm not sure what the symptoms would be.

Going shopping today so might have to push this to the corner and revist later. Right now the grass is getting taller every day.

 

[rentthis]

It may be super flooded. That doesn't explain it running and then suddenly stopping unless the choke was engaged some way or other. Make sure the choke is off, crank it over until the gas stops spraying out and then some. Replace the plug (very important) and retry the spray. If that doesn't work, a compression check is in order. Heck, i would think it would at least stumble start or at least pop with the spray even with a bad ring.

 

[sumpnfishy]

It may be super flooded. That doesn't explain it running and then suddenly stopping unless the choke was engaged some way or other. Make sure the choke is off, crank it over until the gas stops spraying out and then some. Replace the plug (very important) and retry the spray. If that doesn't work, a compression check is in order. Heck, i would think it would at least stumble start or at least pop with the spray even with a bad ring.

I thought about the flooding but I let is sit for a long time between working on it. Even flooded it should fire at least sometimes I would think.

Do you think the plug could be too weak? I see spark but I guess they are cheap enough I'll go pick one up just to give it a shot.
Thanks!

 

[sumpnfishy]

Might have figured this one out finally. As suggested was going to go get a new spark plug and when I went to pull the old one out again to check the number (had done so several times already) it fell apart. Must have had a hairline crack or something. Went and picked up a new one and mower fired up, belches lots of smoke and dies.

I think cranking it so much flooded the entire engine with fuel and there was even fuel in the oil. Pinched the fuel line and got it to start and actually run but it was pumping out a lot of white smoke. Shut down and changed the oil. Started again and ran just fine. Waiting for a nearby thunderstorm to move out before I go mow the lawn but I think I should be good now.

A few hours of frustration over $5 part.

Thanks for everyone's help.
Dennis

 

[redfernclan]

You did right by changing the oil. I have pulled dip sticks on V-8s t hat showed 1 qt overfull because of so much gas in the crankcase. When you check the spark, don't just hold the wire next to the plug or ground. That only checks that you have spark to the plug, not that the plug is firing. Pull plug, put wire back on plug, hold threads of the plug on the engine block and then check spark at the plug. This still is not 100% check because the compression in the cyl makes it harder for the plug to fire than in the open air. But this check is good for 95 % of the time.

 

[sumpnfishy]

You did right by changing the oil. I have pulled dip sticks on V-8s t hat showed 1 qt overfull because of so much gas in the crankcase. When you check the spark, don't just hold the wire next to the plug or ground. That only checks that you have spark to the plug, not that the plug is firing. Pull plug, put wire back on plug, hold threads of the plug on the engine block and then check spark at the plug. This still is not 100% check because the compression in the cyl makes it harder for the plug to fire than in the open air. But this check is good for 95 % of the time.

I actually did check the spark like you mentioned and it was fine. My guess is when the plug was in the block the crack allowed it to short without sparking. Next time I'll just change all the basic cheap parts and not waste time diagnosing.

And I just got done mowing the entire lawn and it runs just fine.

 

[RCW]

A few hours of frustration over $5 part.

Thanks for everyone's help.
Dennis

I just saw this - glad it worked out.

My first thought was change the plug.

Been there, well, you know............

 

[rentthis]

Good news. When my gas equipment fails to start, my peoples first thought is to change the plug. I tell them that it's never the plug. I don't plan to tell them about your repair. Hee hee