I just bought it and knew it wasn't starting, but got a good deal so I took a chance...
It turns over pretty good, it does seem like it has a low or bad battery, even when I jump it, but it does turn over.
Seems like it is getting fuel, there is fuel in the carburetor and I even spritzed a little starter fluid in there, but no luck.
I am getting a spark.
The compression seems good, by the 'ol putting my finger over the spark plug hole and it getting blown back.

Any ideas ?

I just ordered a ignition coil since it was cheap to do...I've tried replacing spark plug and fresh fuel.
CDI box ?

 

I went to check my fuses and one of the fuse boxes has a broken wire, opened the box and no fuse.... I'm wondering if it is intended to be a spare, the fuse box has "PED" on the outside of it...

Anyone ??

 

Upon closer inspection... looks like it was bypassed, the fuse was bypassed and the wire goes straight to the key switch...

 

You say you have spark,new plug also.Shouldn't need a cdi. Thumb pop test isn't the most accurate,but can do in some cases,but best to see that you have at least 125psi or more with a good compression tester. Have to have spark(you say you have),good fuel supply,air,compression and the carb has to be functioning properly. If it's been sitting up possibly the carb is stopped up also. Carb kits aren't cheap for these,but might be needed.2004 Outlander 400 carb kit | eBay As far as the fuse box,detached wire and missing fuse,couldn't tell you,but this site has manuals that can.CanAm ATV and Commander Manuals

 

Thank you o.p.t. ! I've taken the carb apart to inspect it, wasn't dirty or anything... I didn't see any mesh filter (I had read somewhere that there's a mesh filter by the float), the choke and throttle cables seem to work properly...
Even if there were a carb problem, I think the starting fluid would have given it what it needed to at least get a good sputter...

 

That's why I suggested a compression test first. Plus not a bad idea on checking valve clearance also.

 

I did some more troubleshooting this morning and I think it may be the fuel pump. Although I seem to be getting fuel (when I take the line off the carb there is some fuel there)... I got it to finally start by pouring a little gas in the spark plug hole, cranking it with throttle wide open... it would start, runs very poorly for about 20 seconds and then dies. I'm ordered a fuel pump on ebay and if that don't work I will order a carb rebuild kit.

I'll update once I get it going....

 

New coil, new fuel pump, fresh gas, new spark plug....still no start

Gonna rent a compression gauge tomorrow and check compression, what is a good reading ?

 

Just guessing I'd suppose it should have somewhere around 135-140psi at least. Plus again I'd also check valve clearance. Here's what I found on a 2005 model clearances.
VALVE CLEARANCE:
EXHAUST
0.11 to 0.19 mm
(.0043 to .0075 in)
INTAKE 0.06 to 0.14 mm
(.0024 to .0055 in)
I know you said you took the carb apart and it looked good, still may be stopped up,etc. If compression and valves clearances are good,has good spark and fuel supply,I'd head for a carb kit and make sure all passages are clear and blown out.

 

Another question..... when I turn the key on, the cooling fan starts running... is that normal? I would have thought it would not turn on until it is running hot... ?