Could be some debris swirling around in the carburetor bowl getting sucked onto the opening of the main jet and partially reducing the flow of gas to the engine. Remember that the only thing pulling gas into the engine is the air flow through the carb and it doesn't take much to screw that up. (Fuel injected engines have more pressure behind the fuel and generally do better.)
Your carb probably needs to come off and be cleaned as well as the fuel line and tank. Even just bowl removal and a quick clean from there might help.

Check to make sure the splash baffle did not fall off the gas cap. With Tecumseh's I have seen this come through my shop more than once. Take the gas cap off, see if the silver baffle is still in place, if not, look in the tank, move the mower around to see where it is. You will most likely have to take the tank off to get the baffle out(If that is what the problem is) Let me know what you find. Patrick

The procedure for cleaning the fuel metering orifices has been posted dozens of times. In case it's not the tank baffle, remove the brass bolt under the fuel bowl and clean it. There's a tiny hole near the top of the threads that has to be cleaned with a wire from a wire tie. That makes three orifices - a large one through the bolt at the head, a large one down in the center of the hollow bolt and the tiny one. Blast it out with spray carb cleaner and put it back. Use of Sta-Bil is highly recommended in your fuel can every time you fill it. It not only stabilizes today's unstable fuels, it has fuel system cleaners and water absorbers too.

Possibly the fuel tank vent is clogged.
Loosen the gas cap for a few seconds when the problem occurs. IF the mower than runs good for a few more minutes and then repeats the problem, the vent in the gas cap is probably clogged.
It's FREE to check!

Thanks to all. Each bit of advice sounds like it could be a possibility - I will be looking to see if any hit the nail on the head and report back.

Thank you!

As soon as it begins to sputter, loosen or remove the gas cap fast! If it starts to run good again, then my bet would be that the cap is not venting properly. Take the cardboard gasket or fuel baffle out and clean the hole with a fine wire.

Okay - here's the deal:

(and please bear with my lack of terminology:

Gas cap: trying to see if the splash baffle has fallen off. I don't see any silver baffle (per psmsmallengines above). I have a black, rubber piece that is removable on the under-side of the gas cap itself. There is no silver piece. Is the black rubber piece the baffle for this model?

Also - Bill Kapaun above suggests to check the fuel vent. Is the fuel vent in the gas cap itself, I assume? Is the baffle (whether silver or the black rubber) part of this?

Any more detail/insight as I explore this is greatly apprecaited. It would seem that the true test for the fuel venting is when I relieve the cap a bit while the machine is struggling, but I have not had a chance to do this yet. (traveling, now rain!)

Thanks for all the help.

Update:

- I was able to confirm that the splash baffle seems to be intact and clean.

- Venting the cap while mower stuttering did not help. I would say that the fuel is being vented properly.

- On to the carb: Yesterday I had trouble starting from cold start. Every time I primed it would take for a few cycles, but then just die. I would only get a few cycles of run ONLY if I primed, but could never get it going. I tipped the mower carb up, removed the brass nut, which did not look very dirty. I replaced the nut, set the mower down, and it started right up on first pull and ran like a dream for about 30 minutes. It then showed signs of a very subtle sputter, ran for another minute or two, then died on the spot. Same issue upon trying to restart.

- I then removed the brass bolt again. This time, it had carb buildup (a good amount) in the bolt large orifice (i.e., the large opening that hollows out the bolt itself) this build-up popped right out with a piece of wire. Again, the bolt looked pretty good otherwise (other smaller orifices seam clear.)

Now of course, the little washer that seals that bolt in has disintegrated and I need to replace before reinstalling the bolt, otherwise I'm getting gas leak.

I'm thinking that despite a recent tune-up, my carb (and fuel line) needs a cleaning.

PS - I added some STA-BIL to the fuel, but I assume the damage is already done.

Can "bad" fuel foul the carb in just 1 or 2 mowings?

Any insight greatly appreciated.
Brad

What was the nature of the crud that was clogging the jet?

It could be that the fuel line has some crud built up on the inside.
Possibly, if you've recently started using fuel with ethanol, it "cleaned" some of the crud off the line. Another possibility is a piece just "chunked off", or the line itsellf is starting to deteriorate??

IF the problem occurs again, I'd repeat the process with one addition-
After you remove the jet, tilt the mower back on its wheels and let the fuel flush out the line for a coauple seconds.
Often, when working on a carb, the fuel line gets move around a bit, breaking off the internal crud. That immediately gets flushed down into the carb bowl when the fuel flows again.

As far as "bad gas"? apparently anything over 30 days is now considered "suspect".
IF you aren't sure about the quality of your gas, just dump the remainder in your cars tank (where it will be "diluted") and buy fresh gas for the mower.
I only buy about $2-3 worth at a time, depending on how frequently I'm using the mower. I don't have a car to dump the old stuff into, so I keep the quantity I purchase quite small.

Thanks Bill -

Whatever the crud was, it was definitely build-up, not just a piece from somewhere else that settled into the jet.

It reminded me of the inside of a mushroom, sort of a grooved nature to it. completely black.

More importantly, whatever it was, it took about 30 minutes to buildup. Again - I had just added STABIL - so perhaps the STABIL went to work to begin "cleaning" off the fuel line, and the deposits accumulated in the jet?

I'm looking forward to trying this all again - but I need to replace the sealing washer for the bolt. Does anyone know if I can just use a standard fiber washer? I assume I should stay away from neoprene. What size should it be? I'm sure I can pick one up at local Toro dealer, but Home Depot is more convenient.

Oh - and one more important thing: While taking the bolt off to inspect, the bowl came off. Is there a trick to reseating the o-ring for the bowl? I'm having trouble making the o-ring fit into the bowl properly - very frustrating!

Thanks again.

I have a Toro Lx 420 with the EXACT SAME ISSUE! Its been driving me nuts. I was convinced it was a carb issue so i tried cleaning the carb no luck, I thought then mybe something to do with the choke, still exploring the issue but the motor...kohler courage 18, has something called a "Choke shutoff solenoid" ? and I don't know what it does or how to test it. I am excited to find this thread though anyone solved this ?

Funny thing, I have the same issue, but my toro is not shutting off. I replaced the air filter, gas filter, oil and filter, and plugs with no luck. my engine is a kawasaki and sputtered a bit usually after half hour or so. It sometimes lasts for a few or several minutes and goes back to running smooth and then back and forth with the sputtering. Didn't know if it could be a fuel or electrical problem like the plug wires or some type of solenoid or something. I will post back if I find a solution with mine. but will definitely check proper venting in fuel cap and the bolt under the fuel bowl, thanks.

Great news and glad its running good for you! With unleaded gas and electronic ignition, there really is a no 'tune-up' needed. Maintain the oil quality and change the air filter when needed. On my 2004 Lawn-Boy with Tecumseh 195CC engine, I have never changed the spark plug. It always starts on the first pull and doesn't miss, so I don't see any need to touch it. As far as gas, I use mid-range and put Sta-bil '360' Marine (blue) in the can every time I fill it. The first time I had to clean the orifice bolt was also the last time. I did pull it again two years ago and it actually appeared as-new with no carbon at all. The reason I use the higher octane gas is because the 2-gallon can lasts me almost a year. With hot weather and many openings, venting 'volatiles' from the gas, I figure the octane rating steadily decreases. Plus, this combination of regular and premium gas contains better additives than just regular alone.

ECM check pins

Will you help an old veteran? Bought Titan Model # 75302 406712152 zero turn last year. From day one, when I started it, it missed a little then ran OK. It died yesterday. It will start back up & run for 4 second then run so badly you know it will dye. When I operate the coke, it makes no difference. It smokes white/blue fumes as if it is getting to much gas.

What should I check 1st ? Your help will be greatly appreciated.

Had an issue at the beginning of the summer where it would take 7 pulls to start my toro recycler. After much frustration I stumbled on a video about the choke being open. I took a look and sure enough it was stuck open. Freed the mechanism that was stuck and it's been starting on the 1st pull ever since. Reason I post this is when I had the issue it would sound like it was running out of gas and then recover. As TomPlum mentioned this is worth a look.

Thank you tomplum & Woody71 for writing.

Wish I had checked the fuel pump 1st but the diaphragm was busted half into.

Have a new fuel pump ordered. Wouldn't have thought a fuel pump would go our on a 1 year new toro zero turn

thanks guys. tim

I WAS MOWING WITH MY TORO AND WHEN I WENT TO IDLE IT DOWN TO ENGAGE DIS ENGAGE THE BLADES IT WOULDNT IDLE DOWN. WHEN I KILLED IT IT WOULDNT CRANK BACK UP.. I ADJUSTED IT AND THEN IT WOULD STAY IDLING UP AT ALL TIMES. GOT THAT FIXED NOT SURE MY HUSBAND DID IT.. MOWED ONE TIME WITH IT AND NOW IT KEEPS ACTING LIKE ITS RUNNING OUT OF GAS. BUT ITS GETTTING GAS HELP PLEASE.

If it's a Toro it probably has a fuel filter in the fuel line where that line attaches to the gas tank. Clean or replace. Line and filter come as a kit. When you take that line off the gas tank, catch the fuel in short containers with the cap screwed on normally to see if venting is a problem with the cap. Should flow steadily until the very end when it slows down.

also the fuel fittings could be jambing up with derris so blow out the fuel lines ,change the filter

I had a little surprise today - I was using the now 21 yr old Lawn Boy 10684 with Tecumseh 195 and it suddenly started acting like it was running out of gas. I had just finished yesterday washing it, changing oil, changing blade and air filter and cleaning/greasing the rear drive. I used it for an hour before it started sputtering, and there was gas in it. So, I did the old float bowl orifice bolt cleaning but it was perfectly clean - no carbon, no discoloration, just a beautiful brass bolt that looked new. I went to my special/small tools drawer and found the wire tie that had been in there for many years and rodded out the tiny orifice even though it seemed to be clean. I put it back together and sure enough, it immediately started and ran great. I've been running Premium gas with Startron in it for years but perhaps a tiny piece of something managed to get into the small orifice.

BTW, when you go to do this orifice cleaning, stand the mower up on its wheels just like you're going to dump the oil. Fuel in the float bowl runs back to the tank. Typically when you remove the bolt, the float bowl stays put - just watch out for the washer under the orifice bolt head.