Custom Furnace GUI displays incorrect fuel left [1.12.2]

[thedarkcolour]

I have a Custom Furnace block that works like the Smoker block from 1.14. I have gotten everything to work except the flame icon in between the two input slots. Instead of properly decreasing over time, it briefly disappears after a craft cycle and stays full the whole time. The white progress arrow works as intended. Here is an image of what the fire icon looks like while crafting.

It stays like that until the coal runs out.

 

Here are my classes:

 

Tile Entity - https://hastebin.com/qocaxelofu.java    Pastebin - https://pastebin.com/L4G2DMpb

 

Container - https://hastebin.com/zodotevamu.java  Pastebin - https://pastebin.com/MKGQSEdw

 

GUI - https://hastebin.com/sanumopipo.java           Pastebin - https://pastebin.com/TDum28ny

Edited April 5, 2019 by thedarkcolour
Added version in title in case of confusion

[Big_Bad_E]

Use outprints to check of the burnlength is the right value. Send a spoiler with the outprints of k.

[DavidM]

Is it just me or do other people also have trouble going to hastebin.com? The page appears to be blank.

[thedarkcolour]

Added the Pastebin versions of the classes, in case you cannot access Hastebin.

[thedarkcolour]

For some reason 0 / 1600 prints 78.125, rather than zero. It looks like there might be some weird math in my Gui method.

[thedarkcolour]

I have figured it out, the original item's burntime value I use does not work properly ?

[Big_Bad_E]

Always check your values before assuming your code is wrong!