07 Sporstman 500 EFI Backfire?

[Ice_Fishin07]

I changed the spark plug, but after 4-5 miles of ride the ATV started bogging down and backfiring again. Does anybody know what it could be? and How can I fix this?

Thanks a lot!!

[Dave S]

How long has it been since the valves were checked/adjusted or the air filter pulled and cleaned?

[Ice_Fishin07]

I cleaned the air filter recently. The ATV starts backfiring when it warms up or after its been run for few miles. It runs perfect cold.

[NAMASafetyDirector]

Check the exhaust seals (some call it the "donut"). Sometimes they go bad. What will happen is on deceleration fresh air gets sucked in through the leak in the pipe and will ignite the hot gasses and create a backfire. Just something to check....

[charliepete]

I'm not much a of a mechanic, but I had a similar issue with the same machine in the extreme cold. A buddy thought it might be water in the in the gas tank so I ran a couple treatments of Heat through it. I haven't had an issue since. It can't hurt and Heat is cheap so it might be worth a try.

[walleyemaster08]

does it bog down just when you give it gas? I think i got the same poblem on my 07 sportsman efi

[Ice_Fishin07]

Yes, thats what it does.

[NAMASafetyDirector]

Might want to get it in to the dealer and get the fuel pressure checked, sounds like in both your cases the fuel pump may be weak. Fuel pressure should be in the neighborhood of 43 psi (3bar).