Check ebay for the service manual, the factory ones are a bit spendy, but worth it IMO, but another brand such as Clymer sells decent repair manuals for a decent price. As far as your problem goes, it would help to know exactly what TRX 250 you have, the 250R two stroke, or the TRX 250X or 250A both four strokes. Either way there are usually a couple of lines that come out of the carb and just hang open ended. One of them is going to come right off the bottom of the float bowl, that is to prevent the float bowl from aquiring a negative pressure state due to the vacuum created by the intake charge. There is usually an overflow line to let out excess fuel in the event that the float is improperly adjusted or stuck. The overflow tube should come off he left side of the carb. The two stroke carb will not have any vacuum lines, they are only for ventilation and fuel overflow.
Yours truly, sincerelly, love always, Josh aka The DirtDemon.