JD 50 glass fuel bowl system question

[Racer11]

First I do not know the specific term for this,,, The glass fuel bowl is attached to a fuel shut off system that I think oil lines go to it in order for the oil pressure to open the fuel line to the Carb. We replaced the fuel shut off system and on the top is a knurled knob that can be turned either way. But when it is turned down it restricts some movemant of a plunger inside the fuel system and stops fuel flow. Is there some adjustment position for the knob? or what is it for anyway? We found out that with the know turned all the way up fuel would flow and when it came in the box it was turned down and we could not get any fuel flow to the carb. We did some head scratching and pulling hair and ended up turning the knob all the way up and now we have a running engine.

Im making a guess but I think it is for shutting off fuel for long term storage or working on the carb/fuel lines without draining the tank. We have no previous experience on a JD tractor so it is all new to us "City Boys (grin)"

Later

 

[TractorTech]

Sounds about right

 

[lilranch2001]

Not bad “figurin” for city boys!

 

[rScotty]

First I do not know the specific term for this,,, The glass fuel bowl is attached to a fuel shut off system that I think oil lines go to it in order for the oil pressure to open the fuel line to the Carb. We replaced the fuel shut off system and on the top is a knurled knob that can be turned either way. But when it is turned down it restricts some movemant of a plunger inside the fuel system and stops fuel flow. Is there some adjustment position for the knob? or what is it for anyway? We found out that with the know turned all the way up fuel would flow and when it came in the box it was turned down and we could not get any fuel flow to the carb. We did some head scratching and pulling hair and ended up turning the knob all the way up and now we have a running engine.

Im making a guess but I think it is for shutting off fuel for long term storage or working on the carb/fuel lines without draining the tank. We have no previous experience on a JD tractor so it is all new to us "City Boys (grin)"

Later

We had the same system on our JD530 2 cylinder. There is a diaphram inside the glass that is pushed on by oil pressure to open the feed to the carb. I forget what the knob does. Anyway, Alcohol or something in modern gas causes the diaphram to weaken and then fail. Everyone with that style gas tap knows about it. For awhile, JD folk used two diaphrams so it would last longer. The oil pressure has no problem with the extra force needed. There are said to be some diaphrams on the market now that are alcohol resistant . I think I heard of that from Steiner Tractor Parts.
What I did is simply put the fancy oil pressure operated glass gas tap into a nice old box in my spare parts and replaced it with an even older style OEM JD glass bowl type that has a manual lever for on/off to the carb. The new gas tap cost less than a rebuild kit for the old one, and has a core & rubber bowl gasket - but who knows just how good they are - or anything is - against this new style gasoline?
rScotty