yea like normal people myfuel tank rusted through n through, well i went to autozone and bought a coolant res. 1/2gallon tank and connected it to the fuel line, it started up fine for 3 days, then it now leaks from a hose in the back, now it wont start and i got fuel sitting in the airbox box, dont know what the hell happened, im thinking i flooded it idk what to do i just bought this thing

 

Wished I could help you more but really the only info that I can reference off of is the fact you say fuel started comming from a tube in the back, and now the airbox has fuel in it.

First off I want to point out Im not a expert atv mechanic but Sounds like it flooded pretty bad if there is a puddle of fuel in your airbox, take off the air breather, and see if you have fuel comming out your carb. If it is a carb problem I would say its probaly the float is hung, or needle has trash.
If thats the case I would take the carb off and clean it, 1987 model probaly rebuild it.
Shouldnt be more than a couple hour project at most.

I sure loved my 86 model fourtrax, except the brakes they sucked!

Hope you get it going

 

I have an 88' same thing happend. But, i used jb weld on tha tank. Then to have it start floodin out real bad. Noticed that when i pulled on tha throttle' that tha needle was hangin up . And not goin straight throu inside carb. Gas was in airbox, and pourin into intake on motor side. I know it doesn"t have nothin to do w/gas tank but' just sayin

 

i would suggest taking off your carb, cleaning it out with an air compressor real good and making sure your flats arnt stuck, also see if your piston lifts with the needle. if it still does it maybe you have to much of a gas flow going into the carb possably?