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Carb issue

14K views 27 replies 12 participants last post by  Tunezzz  
#1 ·
My lt125 will leak gas out of the bowl overflow, and sputter and run poorly after it has been running for a while. I have replaced the needle valve and seat. The float has no leaks and it still did this even when the float was set to specs. I have tried moving the float down by bending the tab and it still is overflowing and running poorly. It runs perfect for ever if I am going in high rpms but if I drive around slowly it overfills the bowl, overflows, and runs poorly.

Thanks for any advice or help in advance.
 
#2 ·
Does that model have a pri-res-on petcock or just an on-off petcock?
 
#3 ·
The petcock was bypassed before I had it, so the feul comes straight from the fuel pump to the carb. The carb has a primer on it that you pump a couple times before you start it if you haven't ran it for a while. I wonder if the feul pump is overriding the valve and pushing gas into the bowl past the valve.
 
#4 ·
That sounds sorta likely, but i dont know for sure for a few reasons , one being i am not familiar with your model atv and two theres alot of variables in this situation, such as vehicle age and modifiications. Sorry i couldnt be of more help but im sure a more educated forum member will be along to help in a bit. Good luck on that and be sure to tell us how you make out with it!
Have a great nite!
 
#5 ·
It would have to be a hella pump to do that. That needle and seat isn't sealing or the gas has another way round. Did you replace the seat ring gasket so the gas doesn't come around the threads?
As a last resort I'd put it secured to a bench with the float bowl off, put a piece of gas line on the connector, fill it with gas and you hold the floats gently up while buddy huffs on the gas line, you'll see where it's coming from.
 
#6 ·
As a last resort I'd put it secured to a bench with the float bowl off, put a piece of gas line on the connector, fill it with gas and you hold the floats gently up while buddy huffs on the gas line, you'll see where it's coming from.
Thanks! I'll do that!

The needle seat does not screw into place, it just firmly seats into place. The o-ring around it is new, but I'll use that trick to see where it's coming from. Thanks again!
 
#7 ·
After thinking about that I realize that I cannot get gas to the bowl without the bottom half of the carb on. The gas line connects onto the bottom half (bowl) and travels up into the top half (carb body) through a tube, where it then goes to the valve. Where the gas goes from the bottom to the top half could be a trouble spot, allowing gas to leak past the gasket into the bowl.
I hope this image helps:
 

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#10 ·
Another possibility is fuel pump diaphragm is leaking back through the pulse line and into the carb.
I think this could be the problem. It is flooding worse than ever now and barely runs. I need to get it fixed as I want to sell it. I pulled the vacuum line off after running it and there was moisture inside. A feul pump is 80 bucks. Is there any way I can rebuild mine? It has had this flooding problem solved nice I got it and now it's getting worse. I think the pump is going south.
 
#9 · (Edited)
The gas line goes to the primer and then into the carb. If I pinch off the line it won't get gas.

I'm at a loss. I traced the gas line into the carb and sprayed cleaner into all holes and put it under pressure and I can't find any place where gas is leaking in. I've had this problem since I bought this quad and that's probably why the guy sold it. Maybe I'll just buy a new carb.
 
#11 ·
I ordered a new pump for $86. Took the vacuum Line off at the pump and gas came out. Hope this is the fix because I got a couple guys that want to buy it when it's fixed. When the time comes, I Probably won't want to give the old girl up!
 
#12 ·
I didn't fix it! I have over 700 in it with this past rebuild and the carb issue is still present. I took the carb part for the 10000000000 time and i took the needle seat out. The thing barely fits in the hole with the ring on it. In fact it won't fit without the oring trying to roll up and it's shredding apart. I have replaced every part that it could be. I don't know what to do next. New carb?
 
#14 ·
Thanks for the tip!
 
#15 ·
some time the float is bent and goes to high or too low and keeps letting gas in. when I got a used lt160 I bought a rebuild kit but it did not come with the float. I bent and straightened it 5 times until it ran right. yes that means taking if off and apart and back together each time.
 
#16 ·
I have both floats set to the right level and I've tried different heights. It's obviously getting in somewhere else.
 
#17 ·
Went back through it Again. This is such a simple carb. What can I possibly be missing? Is the needle supposed to have a rubber tip on it? This problem is really frustrating.
 
#18 ·
Some do......some don't.....if it is all steel and comes to a complete point then it doesn't....if it does not come to a nice point and not sharp, then the tip could be missing
 
#21 ·
Nope.
 
#22 ·
It's been sitting in the shed since I got my king quad. I am buying a used carb from a member on the forum. Still trying to get it fixed.
 
#23 ·
Got the used carb and had a hard time getting the machine started. It would start, die, start, die. I took the carb and checked the float. It was nearly a quarter inch low, so I raised it to spec, which is 1 inch exactly. Put the carb back on the machine and lo and behold... the machine runs OK but the carb overflows. What do I do, but take the thing on and off for another hour, progessively lowering it further off spec. No change. So Im back to square one with this thing. Im going to keep messing with it but I cant figure out why it wont work at spec.
 
#27 ·
Fuel can only dump out of the carb if the supply is not being stopped. So what stops the supply? Needle and Seat. These components are under the float hinge and operated by gravity and the float. If the needle doesn't seal up inside the seat, fuel will leak past it and then either out the front of the carb or into the engine.

Into the engine can damage the engine because while rings are a decent seal, they will still allow gas to seep down around them and into the crank case.
 
#28 ·
You're not wrong. I just didn't know if it was dumping out of the main drain, or the weep hole on the primer itself. I had an issue that it would dump constantly out of the weep hole until it was completely warmed up. It was odd, but I just thought I would mention it just in case others had that same issue