Two fuel lines to the carb?

[theswede]

Hi!

I have gone and bought me a new carburetor for my scoot, and am confused about how to hook it up.
My old carb has two connections, fuel in and fuel out (bowl drain).
The new carb has three connections, and though I can make out which is fuel in and drain out, I am not sure about the last one. Maybe its not even for fuel but for vacuum? Hopefully someone here can help me...

Some pics:

This is the underside of the bowl. Upper left is the drain, lower right is the unknown connector.


Bowl inside. The small hole at the top of the picture is where the unknown connector ends inside the bowl


Carb underside with float. The crescent-shaped indention at the top matches the same indention on the bowl. It doesn't seem to lead anywhere?

[shiftless]

Thats a first for me,
In the pics, it appears that the hose in question makes a dead end in the gasket
A vent maybe
I'd plug it and see if it works properly
Maybe someone else has seen that setup and will chime in

[Rebel]

I think t is a vacuum line, think is the operative word here. Why you would need vacuum here? I don't know but it looks like one to me. so plugging it might not be a bad idea, if it does not run well plugged, hook it up to vacuum and see what happens. The mating surface on the top half of the carb, does it have a hole there going to something else?

[theswede]

I am leaning toward the vacuum line theory too. I had an e-mail form the seller today, I asked him the same question but unfortunately his English isn't all that good so I am having a hard time understanding what he meant. He was talking about vacuum though...

There is a little "button", maybe a valve (?) on the top half of the carb that possibly matches the surface inside the gasket. I have circled it in red in my last pic.

/Otto

[Rebel]

If you know the make and model of the carb, do a google for a manual on it, the manual should specify what it is.

[theswede]

The model is PD20J, make is unknown. It is almost 100% identical (except for this extra connector) to my original 139QMB carb.
I remember reading somewhere these are Klein clones?

Anyway, I have googled quite a bit and I still can't find any useful information. Hence this post...

/Otto

[Rebel]

I see well after looking at your response to my last question, I'd certainly hook it up to vacuum, looks like a vacuum thing to me.

[theswede]

Thanks guys,
I'll give it a try as a vacum line connected to the intake and see what happens.

/Otto