2-105 Upper tank- lower tank

CP1 · Nov 3, 2017

Have a 2-105 White and just wondering how the fuel is drawn out of the lower tank. See 1 line with a shut-off coming from the rear of the lower tank. And the lower tank has a non-vented cap. Just wondering the 'theory' of how this works together with the upper tank??
Thanks

rrlund · Nov 3, 2017

The engine creates a vacuum in the upper tank to draw the fuel up from the bottom tank I believe. That's why the vented cap goes on the bottom and the non vented on the top tank.

IanC · Nov 3, 2017

It depends on your serial number. Early machines used the system Mr. Lund explains, later machines drew from the bottom tank. Go onto agcopartsbooks.com and look up the system your serial
number uses. Putting the wrong cap on the wrong tank can (will) collapse your fuel tank.

oliver1755 · Nov 6, 2017

I have a 2-85 with the setup drawing from the upper tank. I have had the tractor a year and have not ever gotten it to draw up from the lower tank. Two new non-vented caps on the upper tank, new vented cap on the lower tank, new lines, check valve, etc. I can draw fuel by suction on the line, but cannot get it to work on it's own. The prior owner had an electric pump in the line from the lower to upper tank that I took out as I thought I should be able to make it work. That being said, in the last few days, I reinstalled this pump and am waiting for a switch to put on the dash.

I don't know if I've gotten two bad caps or what, but it just doesn't want to work. The second cap, I know for sure, wasn't good as the tank leaked from it. The first one has never leaked and "should" work.

The 1855 with fender tanks works just like it should. Not sure why I can't get this one working.

CP1 · Nov 6, 2017

I think it is dawning on me how this works... the top tank is sealed so no air is drawn in. Where a normal tank, when fuel is used out the bottom air is drawn in the top. A suction, caused by fuel used up out of the upper tank, draws fuel out of the lower tank to replace the fuel in the top tank. So the top tank would always remain full until the lower tank is empty. Interesting concept! But you have to have a good cap on the top tank, so there is no air drawn in, and a good vented cap on the lower tank to let in air! Since a Diesel engine creates no vacuum, it is all dependent on a tight system to create a suction in the top tank

2-105 Upper tank- lower tank

CP1

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rrlund

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IanC

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oliver1755

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CP1

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