1997 Polaris Sportsman 400. Need fuel system diagram listing filters. I have drained old gas, changed spark plug. Do I need to remove carb and clean? Help or suggestions are appreciated!! Thanks,

check cap vent -fuel filter - valve - carb problem

Old fuel, dirty carb jets. Low fuel level in carb. Has it been sitting up? Check air filter and plug.

Hi Arlin:
Here's a link that should help you.
https://www.google.ca/#q=remove+the+gas+tank+on+2004+polaris+sportsman+400+atv+youtube
heers

Check air filter make sure its clean, fuel lines are clear and filter clean or new, is the gas old? Carb or injector? if carb possible needs cleaning. could also be fowled plug

Replace spark plug (gap correctly),Drain all fuel, replace fuel filter, replenish tank with fresh fuel, do a thorough readjustment of the carb settings (last resort - remove and rebuild carb)

Its either needs the fuel system, including professional carb cleaning, or there is a ignition system problem.
Its probably the carb!!!!!

replace fuel filter. check spark plug. fuel has waste in it bad fuel maybe.. has it been setting a long time. remove sediment bowl from carb. should at least drain the carb and catch the fuel from the drain. examine fuel caught for bubbles in bottom of fuel container. air filter clean? adj timing ? does it smoke when running? backfire? choke off ?

did you check the float height?

If your atv has been sitting this long, the carb is probably stopped up internally... take the carb to a qualified professional and have it cleaned and set...(take a few pictures so you know where all the hoses re-attach)

ALL it takes for an engine to run is:
1. A timed spark
2. Adequate compression
3. Proper fuel/air ratio delivered

All most positive it is in your carb take the bowl off it as you take it off there is a small tube that hangs down that all most reaches the bottom of the bowl need to take a small wire and push through it it is blocked .symptoms backfiring no idle coughing and sputtering if it does start