What's wrong?

[ukrkoz]

I have flail mower with this engine:

15 hp 420cc JiangDong electric start
That engine is basically Honda knock off.

Everything worked fine till today.

I towed mower out into the filed, started it, start mowing - after about a 100 ft, it dies. Engine shuts down. Start it again - starts fine. Start mowing - engine sputters and dies.
And keeps doing this - starts, runs fine, start moving, what means - mowing - engine dies. Dies like as if fuel supply cuts off. But don't listen to me.
I tow it back to where it normally parks, check on every thing - all appears to be fine. Start, stand there for few minutes - runs fine. Start towing mower - dies. Starts and starts dying - so on a hunch, I opened gas tank cap. PRMs jump up, engine appears to run fine. Put cap back on - engine dies after some time.
So out of desperation, I leave gas tank cap not fully tight - mower starts mowing. Sounds abit strained, I just go slow, but it mows. Didn't stall even once. Gas cap undid itself several times during 1 hr mowing, but, otherwise, I finished what I needed to do.
Parked mower, tightened gas cap.
So I figure, it has something to do with fuel supply?
Air filter is clean.
I had tank topped before I started mower, but I had same last time, without any problem. Does it have like a fuel pump or something? Or it's simple gravity feed into the carburetor?
Gas tank has cap and what appears to be fuel filter at the top - black flat plastic piece in rubber grommet, with barb for the fuel line. Fuel line is not pinched. I could not pull that piece out, I tried. Thought, maybe filter got clogged...
Any ideas? Of course, I sold my ZTR last week, confident that I have running mower and, surely enough, here we go.

Thank you.

 

[Kyle_in_Tex]

Make sure gas cap is breathing.

 

[buckeyefarmer]

Yep, loosen gas cap. If it runs, cap vent is plugged.

 

[ukrkoz]

Where's cap vent then? I have no problem cleaning it.
There's no holes in it or else

 

[ukrkoz]

That's what I have.
What to clean? It's super basic.

 

[ukrkoz]

Bump. No one?
Also, anyone knows how to get that black Depurate thing out and what exactly is it? Sounds like filter. I tried to pry it up, even with tools - no go. I don't want to break it as then I am really hosed.

 

[WranglerX]

Should be something like x 1/16 hole someplace in cap.... OR maybe on "DEPURATE" (filter?) where line connects at corner of tank ....

Dale

 

[Kyle_in_Tex]

That's what I have.
What to clean? It's super basic.

Somewhere, under that cap (where you can't see) should be a tiny breather hole. Maybe try cleaning with air pressure pointed from all directions underneath?

 

[ukrkoz]

I'll look again. Surely, I wear glasses, but I'll take my stronger ones with me next.
Any idea how to get that Depurator thing out? Prying on it up, even with screwdriver, didn't really help. And if I break it, I'm dead. As it likely has fuel line attached to it going to the bottom of the tank.

 

[ukrkoz]

Ok, no hole in the cap, positive. the only breathing I can think of is 2 notches in the cap edge on either side of the metal "wall"
Maybe the rubber gasket swell from gas or something, and covers them

Also, here's kicker. I got Depurator out. After prayers and such. Gods were merciful. Apparently, this thing runs on vapor. As Depurator is not fuel filter and does not have fuel line that goes into the tank. It's simple basic vacuum operated valve. Will allow air out, will not allow it back in. Maybe when I over filled tank yesterday, I flooded it and it got stuck?

Cleaned both cap and Depuarotr with spray cleaner. Engine started and ran for some time. I don't want to create much racket, it's 8 am here Sunday.

 

[rangerfredbob]

Is it low on oil? those engines usually have an oil level switch that will shut the engine down, usually by the manual kill switch, I think if you just unplug it it should stop doing that since it grounds out the coil when low. The chinese copy engines are bad about that when used in odd angles they can false trip which kinda sounds like what you have going on.

 

[rangerfredbob]

I've also ran into goo that is moving around the float bowl in the carburetor will get into the fuel supply hole at the bottom but too big to be sucked into the jet then falls off until you hit the right bump...

 

[ukrkoz]

Is it low on oil? those engines usually have an oil level switch that will shut the engine down, usually by the manual kill switch, I think if you just unplug it it should stop doing that since it grounds out the coil when low. The chinese copy engines are bad about that when used in odd angles they can false trip which kinda sounds like what you have going on.

I'll check oil, pretty sure it is good though, I checked before last mow. But I have no idea where it is, as I have no idea where manual kill switch is. I have Choke/Fuel supply/ RPM/ Ignition key.

 

[ukrkoz]

I've also ran into goo that is moving around the float bowl in the carburetor will get into the fuel supply hole at the bottom but too big to be sucked into the jet then falls off until you hit the right bump...

With about 15 hrs of mowing? Goo already? I'll run Seafom through next. Strong medicine.

 

[ukrkoz]

Oil is good. Was actually overfilled a little.
I poured some Techron type stuff into gas..

 

[Kyle_in_Tex]

Sometimes, a motor that gets bounced around too much can flood out.

But I still believe it's a gas cap issue primarily.

 

[buckeyefarmer]

There has to be a vent somewhere, or the tank builds up pressure, and then it stalls. He proved that by loosening the cap.

 

[RandyT]

I also replied on lawnmowerforum but all lawnmowers manufactured after 2012 have either non vented caps or activated charcoal containing caps since you can't allow unburnt gas fumes into the air. The black plastic thing on the corner of the tank is the vent which will either go to a charcoal canister or to the air filter side of the carb for vapor recovery. The problem is when they get gas contaminated they will brick the material inside and will not allow air flow in either direction.

 

[ukrkoz]

I also replied on lawnmowerforum but all lawnmowers manufactured after 2012 have either non vented caps or activated charcoal containing caps since you can't allow unburnt gas fumes into the air. The black plastic thing on the corner of the tank is the vent which will either go to a charcoal canister or to the air filter side of the carb for vapor recovery. The problem is when they get gas contaminated they will brick the material inside and will not allow air flow in either direction.

Ok, so Depurator black piece on the side is vent, not fuel line. Though it allows air only OUT of the tank, not INTO the tank, so how exactly does it vent it?
Gas I put in is Costco ONLY, I have best priced. It's same gas I use in my cars for years.
So there is fuel line somewhere else then, right?
I'll track where that Depurator line goes.
One thing about this mower it always ends up being covered in all kinds of fluffy stuff. Old dry grass clippings, forgot the proper word... Air filter pre-filter, sponge type, was also half way covered in that stuff, but I cleaned that before I even loosened the gas cap.
Does it make sense to unplug the Depurator tube then? Let it breathe into the air? Instead of some canister or else...
I saw yesterday that all small engines are made to CA standard, so basically chocked as much as possible.

 

[buckeyefarmer]

I am not familiar with that kind of setup.