I have a TG1860G lawn tractor with the 18 hp Kawasaki engine. Recently, gas started leaking out a black plastic line that comes from the top of the carburetor. It leaks both when it is running and when it is shut off. My first guess is that this is an overflow line and the float in the carburetor is not completely sealing. The odd part is that what I say is an "overflow" line is so high up on the carburetor. It's above the air intake part. This would indicate to me that the cylinders and everything would have gas in them, yet the tractor can be started up and runs fine...it just still leaks gas out that line. How can I fix this problem?
TG1860G with fuel leak
- Thread starter musgjerd
- Start date
Wow! this was a super reliable engine and one of the first post I've ever seen about this problem (and I'm a real Kubota nut ). I owned a diesel TG but will look in my work shop manual to see if the gas engine is there. Could you up load a picture of this black plastic pipe please? 
Here are a couple pictures. The line I was speaking of is not the one my finger is on, but the one just to the right of it.
Since my original post, I have taken the carburetor apart and cleaned it pretty well. Now, when the engine is running there is no leakage. But, as soon as it is shut off it continues to leak out that black line.
Since my original post, I have taken the carburetor apart and cleaned it pretty well. Now, when the engine is running there is no leakage. But, as soon as it is shut off it continues to leak out that black line.
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Under the fender deck on the left ( Drivers side ) there is a fuel cock try closing it off when you shut down and see if it still drips.... does the hose come off the carb bowl I can't tell from the photo... it looks like its right below the air cleaner housing? We will figure this out, I got friends in Kubota places....
I sure hope we can figure this out. I have been shutting off the fuel cock after running the tractor, and that does prevent it from leaking. But, it leaks all over before the fuel cock gets shut off.
You are correct in that the line is directly below the air filter, right at the very top of the carburetor. The line could come off the carb as it is held in place by a spring wire (normal hose clamping device).
As I look at the carb more, I notice an electrical device at the bottom of the carb. Upon further inspection, is appears to be an electrically operated needle that fits against a seat....much as a float would do. Could this possibly be an electrical problem?
Does anyone have a diagram of this carburetor?
You are correct in that the line is directly below the air filter, right at the very top of the carburetor. The line could come off the carb as it is held in place by a spring wire (normal hose clamping device).
As I look at the carb more, I notice an electrical device at the bottom of the carb. Upon further inspection, is appears to be an electrically operated needle that fits against a seat....much as a float would do. Could this possibly be an electrical problem?
Does anyone have a diagram of this carburetor?
Okay I want you to try this before you give up on Old OB1, start her up and wait for the gas to start coming out the overflow ( that's exactly what it is by the way ) and open your fill cap up slowly ( don't take it off just crack it good ) and see if the fuel stops coming out the plastic vent. You may have the system vent plugged in the fuel tank cap and the fuel system is venting at the overflow vent instead of the cap.... I really feel stupid about not thinking of this before now..... let us know...
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As I look at the carb more, I notice an electrical device at the bottom of the carb. Upon further inspection, is appears to be an electrically operated needle that fits against a seat....much as a float would do. Could this possibly be an electrical problem?
That's your fuel shut off solenoid and I really believe if it was shorted the engine wouldn't run at all......
That's your fuel shut off solenoid and I really believe if it was shorted the engine wouldn't run at all......
This is getting harder to diagnois. At first, gas would come out the overflow while it was running. After a few days that changed and gas would only come out the overflow after the mower was shut off. I did try loosening the gas cap as was stated above, but it had no effect. At that time gas would only come out the overflow after the engine was shut off. Now the problem has changed a bit. Now when the engine is shut off, there are only a few drops that come out the overflow line, but quit a bit of gas comes out the top of the fuel pump. There is a little hole at the top of the fuel pump where gas comes out. Could all these problems stem from a malfunctioning fuel pump?
I'm thinking that hole in hte fuel pump is a vent for the diaphram and would only leak fuel if the diaphram has a hole in it! But I could be wrong as I have never owned a Kaw motor.
Musg are you sure the carburetor float, needle and seat are 100% correct? Have you had the Carb apart to install a kit? These little one barrel Kawasaki carbs are very sensitive to governor adjustments, choke position and WOT settings. As far as the fuel pump it is self regulated for correct psi. This puts us back to the fuel shut off solenoid. Can you measure any resistance in the coil?
Oh great Ob1, I have not installed a kit in the carburator, nor have I adjusted the governor or any other setting. I assume the float, needle and seat are fine, as it has not been taken apart. That doesn't mean that there couldn't be a chunk of something in there preventing it all from working properly. I did check the automatic fuel shut off by starting the engine and then pulling the electrical wire to the shut off. The engine quit immediately. Of course, that doesn't mean that there isn't a small leak past the shut off. I also ran a can of sea foam through the fuel system. This seemed to move the problem from gas running out the overflow line (only after shutting the engine off, not when running) to now leaking out the breather hole in the fuel pump. I see only a couple drips coming out the overflow line now. Most of the leaking gas is coming from the fuel pump, and it kind of pulses out (not a steady flow). There was a suggestion that there could be a hole in the diaphram in the fuel pump. Can I just replace the diaphram by taking the fuel pump apart, or would I have to buy the whole fuel pump?
Ole Musg please....my make up is running down my cheeks with gratitude. I'll check tomorrow with Carver but I'll bet you will have to go to the pump vendor to get the diaphram. I think all Kubota will do is supply the whole pump. Well since you used the Sea Foam and the problem moved somewhat I still think we are flooding the carburetor bowl and all these pheomenons are symptoms of that problem. I'd buy a Carb before the pump because the engine runs great at WOT. It's at idle and unloaded speeds that you see the problem right? Just shut the valve off under the fender deck and run it out of fuel before you tear into anything for safety The problem only exists after shutting off the engine, now. I have no fuel leak when idling or WOT.
Did we talk about the vent in the fuel cap? Blow it out with 5 psi of shop air from the inside out. ( reverse of how it vents). If you have a line coming off the base of the fuel pump going into the crankcase base take it off and clean it with Carburetor cleaner ( Gumout ) as a last resort shut the fuel cock valve off to stop the leak until you can off season pull the entire system down part by part and you will find it Musg....
I haven't been on here in quit a while, only now again because I am doing research on a different problem. I just read through this old post of mine and figured I would add information on the outcome of the problem in case anybody pulls up the old post. The problem ended up being the fuel pump. It had a leak in the diaphram. I could not find anyway to just replace the diaphram, so I ended up putting a whole new fuel pump in, and everything works just fine. I think the pump cost me about $145, but it solved all my problems.