Sit-on-top lawn mower. Zero-turn radius mower, 50" mower deck, hydro transmission.

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Wont stay running for more then 20 seconds

Mower wont run for more the 20 seconds no matter what i changed new plug,starter,clyinoid,and new kill switch any ideas

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Sounds like a fuel issue. Does your mower restart immediately after it stalls? For those 20 seconds the engine actually runs or is it stalling etc.? I'd start with considering a stuck float.


I had the same problem. Stripped the carb down and found the float bowl was full of waxy beads like wet silica gel which was jamming the float. Cleaned it out, blew through the jets with compressed air, put it all back together and now it runs better than it has for ages.


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tony alexander, Possibly easy fix. Before applying oldturkey's good suggestions, remove the gas cap and see if engine runs better/longer. If it does this signifies a plugged gas cap vent and is quite common. Dirt and dust can accumulate and eventually plug the vent hole in cap which will restrict fuel flow and can cause engine to quit.

Good luck. I hope this helped you out, if so let me know by pressing the helpful button.

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tony alexander this sounds more like a fuel delivery issue. So I'd focus on the carburetor i.e. stuck float or needle valve as well as checking the intake and exhaust valves. The ZTS7500 comes with Kohler as well as Briggs and Stratton engines (should be a 44P777-0130-P1 or 44P777-0130). The Intek™ OHV V-twin utilizes a fixed jet, two barrel, side draft, flo-jet carburetor. Except for idle speed, the carburetor is non-adjustable. The carburetor incorporates a fuel shut off solenoid which controls fuel flow to the fuel metering system. The solenoid is controlled by the ignition switch. Try and see if you can give us your engine make and model so we can get more information about the fuel system.

Block Image

is a typical diagram for a B&S 44P700 engine carburetor #133 shows the float

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The symptoms described is a signature issue on this type Briggs 6.5 Carb (and others that use it)

If any debris gets in the fuel and fits thru the float valve it settles at the high speed jet that is at the bottom of the fuel bowl. In fact it is the brass piece that holds on the fuel bowl to the carb.

I find it best if it comes down to having to fiddle with this jet, to remove the carb, get some Lacquer thinner and a small brush and thin wire and really clean clean clean all dirt off the outside. Then throw that Lacquer thinner away, clean the container and take the hi speed jet screw out of the fuel bowl. If you are careful and gently pull things apart, hopefully you can save the rubber gasket between the bowl and carb. If it sticks, wd40 it with spray and keep working it off.

Next, Ya gotta have some air pressure to blow out the carb, and you first should let it soak for a while. Take the float off and shake it to make sure there is no fuel in it. If it is leaking and I have never found a plastic float that leaks, it will have to be replaced.

Once the carb has soaked, wire out all the holes and then soak again and wire again, and then blow out every hole you see. Make sure to put the air tight against the float valve hole.

Reassemble, the reverse of taking it apart, reinstall, and next, Clean the filter with air and clean the filter holder with the left over carb Lacquer thinner, so that you are starting out clean.

And don't take any short cuts trying to prime and start the engine without reassembling everything. All the parts including the filter are required to be installed to get the silly thing to run.

Prime it with the prime bulb and pull away!

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Before you disassemble anything, try this -- it worked for me.

Buy a can of Seafoam gas treatment (, put some in an empty gas can, and fill the can with new gas. Drain the gas from your tank. Swish the gas can to mix the seafoam and the gas, and fill the tank with the seafoam/gas mixture. Now start your engine.

After I did this, my lawn mower ran like new. It still is, months later.

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Winner winner chicken dinner. Toro with 6.5 b&s engine would start up 1st pull and stop 3 sec later.

Read jim phelps answer and it sounded good to me.

I had startron small engine fuel treatment handy. Pored about half an once into empty tank then about an ounce of gas. It did the start stop thing about 4 or 5 times but noticed the run time getting longer. Once st struggled running for a minute or 2 it got smoother. Filled the tank and let run for 5 min. Smooth going.

Then i cut grass.

Thanks Jim!


Glad you got it fixed without having to disassemble anything.

Seafoam is a miracle cure for clogged fuel systems. If you ever can't get the system unclogged with some other product, try Seafoam.


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tony alexander will be eternally grateful.
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