I recently bought a 2008 kfx450r with a full Yoshimura exhaust, K&N airfilter, removed lid, and power commander. It ran very well for about a week and now I am having trouble with it.
It starts right up but only idles for 3 seconds before dying. If I start it and nail the throttle I can get it to run for up to 20 seconds but it dies after that (I dont think its too good to do that anyways).
I tried using the high idle/choke knob and it does the same thing. I unplugged the power commander and the problem still exists. The TPS voltage was at .55 so I adjusted it up to .68. I checked the sparkplug and it looked OK but I replaced it anyways. I'm not sure if it's related but when I turn the key and then slide the switch near the start button the fuel pump runs for about 5 seconds and then stops.
These problems started yesterday but the day before when I was riding it it would die after running hard and then slowing down or taking turns.
I have a feeling it's either something really simple like a shorted wire somewhere or something major like the fuel pump. Any ideas?? I love the quad but I just want to ride it!!