Kohler XT7 Engine Runs gas through it, of course won't start

crappy_kohler_xt7

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  • / Kohler XT7 Engine Runs gas through it, of course won't start
From the post directly above, I am also having some auto-choke problems. Once started, I already have my air cleaner off and have to hold the plate open for 30 sec or so or the engine will flood out. I have to run it for about 3 mins standing(not cutting grass) until the heat from the exhaust/choke control keeps my plate open.
 

bootface

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  • / Kohler XT7 Engine Runs gas through it, of course won't start
Yes, this is a Chinese engine. I think it's the same engine as the one used on new Ariens and suffers from the same problems. They are hugely over-engineered, especially the ones that have an automatic choke - I've seen Ferrari's with less complicated mechanisms. I don't think any of the answers in this thread will fix the problem. Bear in mind these engines aren't much older than 12 months and gunge build-up in the carb does not apply. In my experience (and I have worked on many of these engines this year) the only solution is to replace the carb. You cannot replace any of the components because they are not sold separately (at least according to my Kohler dealer). You cannot even buy a float bowl gasket. I know this is not much help but these engines are bad news.
 

bootface

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  • / Kohler XT7 Engine Runs gas through it, of course won't start
Yes, this Kohler engine is made in China. However, with the greatest respect to my fellow "experts", you are all missing the problem. The float and fuel needle have nothing to do with delivering fuel into the engine. They exist simply to ensure that the supply of gas from the tank into the float chamber is kept at the correct level. Floats and needles don't go wrong very often. Despite what everyone says, the needles don't stick unless they have been left sitting for 2 years with old gas and get gummed up. For normal mowers used normally, needle sticking rarely happens. The biggest problem relates to the float bowl gasket. Many of my fellow experts don't understand that carbs work on the principle of atmospheric pressure and vacuum. The pressure of the air rushing into the venturi to fill the vacuum caused by the descending piston, is different from the normal air pressure because it is being squeezed into a smaller opening and, therefore, runs faster. If the atmospheric pressure in the float chamber remained the same as normal, the rushing air in the venturi would push out through the float chamber via the gas feed line. Obviously, this aint going to make anything work. So, there's a small airway (called an "air bleed") from the venturi into the float chamber which ensures that the same atmospheric pressure that exists at the venturi, also exists within the float chamber. The forces of nature take over and a small amount of gas is drawn into the venturi where it meets the incoming stream of fast-running air and, whoop-di-do, mixture and vaporization commence. If, and this is the important issue, the float bowl gasket is not working properly, air is getting into the float chamber through the gasket and negating the atmospheric pressure coming in from the air bleed. In other words, the gas won't be pushed in to the venturi and the engine won't start. Even on carbs where there is a manual primer (and the old Tecumseh engines are the best example), pumping gas into the venturi will start the engine but it will stop straight away if the float bowl gasket is faulty. This same faulty gasket will also cause the gas to leak. Now, having said all this, the problem is not necessarily going to be fixed by replacing the gasket. In my opinion, these gaskets on this engine are too thin and don't get properly compressed when the bowl nut is tightened. So, a new gasket may work but it may not. Just make sure that the gasket seat is clean, as is the inside rim around the bowl. Use solvent and a soft brush to clean. Don't use a wire brush. So, for those that have taken the bowls off, fiddled around with the pin, cleaned the float and put it all back together to find the machine starts. All you have done is to reposition the gasket and fixed the air leak. The needle and pin had nothing to do with it. The only air getting into the float chamber must come through the air intake side of the venturi, not through the gasket.
 
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ILENGINE

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  • / Kohler XT7 Engine Runs gas through it, of course won't start
I see so many errors in your explanation I don't even know where to start correcting. Somebody needs to go study carb theory, and find out what all those passages are really for.
 

chance123

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  • / Kohler XT7 Engine Runs gas through it, of course won't start
I've done a quick search and have seen this as a problem on some XT7 engines. Less than 4 hours on it, always has been hard to start and now gas just pours through it out the carb. Any ideas I can try?

Thanks

Hmm. Judging by this first post, If the fuel pours through it, "clearly" the float needle is not stopping the fuel. When running, and as the engine consumes the fuel from the float bowl ( reservoir), the float will lower opening the float needle and refilling the float bowl to a constant level. If the fuel as JSmith says, is just pouring out the carb, there has to be a problem with the float/needle & seat system.

edit: I guess if you had excess pressure in the fuel tank, "that" might over ride the float/needle,& seat.
 

bootface

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  • / Kohler XT7 Engine Runs gas through it, of course won't start
I agree. If the needle is stuck open then fuel is going to keep coming in. However, I have found that it's rarely the needle. Perhaps the float itself is punctured and is not rising to shut off the needle? I guess we need to know where the gas is coming from. Is it coming out the air intake in which case it is definitely flooding in the bowl. If its dripping from the bowl then it could be either the securing nut or the drain nut loose or the little rubber gasket on either is broken.
 

chance123

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  • / Kohler XT7 Engine Runs gas through it, of course won't start
Not familiar with the China Kohler. I am wondering if it has a replaceable seat. I remember on some other engines of the past, those small rubber seats that have a ridge on one side (goes in first) and if I were to put it in upside down, it wouldn't seat with the needle, because the "correct side" has a shape that conforms with the needle. It is hard for me to stomach Kohler being made in China! Bring jobs back home and return quality again. I haven't worked on a Wisconson (VH4D etc. and the Robins) engine in years, are they still in business?
 

bootface

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  • / Kohler XT7 Engine Runs gas through it, of course won't start
Don't know about the ridge on the seat. In any event, I spoke with a Kohler dealer today and it seems they do not sell any carb components for the Chinese machines. You have to buy the whole carb. This is disgusting. I was quoted $55 for a new carb which does not include the gaskets on the air intake or the exhaust manifold. These have to be purchased as gasket set which also includes the head gasket. What a rip off.

I also have a Yard Works machine with carb problems. When you strip off all the cowlings, the engine underneath is identical to the Kohler engine. The carb shape is the same. The only difference is the choke. The YW machine has a B&S wand, whereas the Kohler has a heat activated spring piece of riubbish. Basically, they are the same engine. So, given that MTD owns Yard Works and they are now making stuff in China, and now Kohler is buying Chinese engines instead of making them, it looks like before long every lawn mower engine will be made in China. I also have a Husqvarna in for repair. Guess where it is made?

What is wrong with our stupid country? Why don't we stand up and say we've had enough?
 

KennyV

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  • / Kohler XT7 Engine Runs gas through it, of course won't start
I see so many errors in your explanation I don't even know where to start correcting. Somebody needs to go study carb theory, and find out what all those passages are really for.

I agree with you...
... there is Only one source of excess fuel to the carb, the float needle is not stopping the fuel....
:smile:KennyV
 

HIgh Rustler

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  • / Kohler XT7 Engine Runs gas through it, of course won't start
I am having this exact problem as well. Had a toro 22 inch large back wheel self propelled 2003 that finally died 2012. B/S engine, never got that kind of life out of any other type of mower so bought another one, this one with the Kohler. Had this problem this past march bad, finally would not start at all. Local shop replaced carb for about $100 and I went on my way.

Is this mower/engine just a lemon? really souring me on toros. Is there a fix yet? any insight appreciated. Meto atlanta Thanks very kindly!
 
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