I have a 2005 Polaris Sportsman 800 EFI with about 1500 miles on it. When engine is cold it takes a long time for the ATV to start. Seems to crank just fine but takes a long time for it to start. Once running RPM's fluctuate from around 800-1200. If you punch the gas it seems to hesitate for a bit and then will either kill itself or slowly start to rev up. Also when driving down the trail it will sometimes lose power and start sputtering and loud popping noises can be heard coming from the airbox. Once the engine heats up it seems to run better but still isn't right. I have read other posts where people were having similar porblems and recommendations were to change T-BAP wire harness and also to clean the throttle body. I have done both these things as well as changing the plugs, running fresh 91 octane gas with Sea Foam through the motor, and also cleaned my K&N air filter. Still nothing has seemed to help my problem. Any advice or tips would be greatly appreciated as I have been battling this problem for quite some time.

 

Did you check to see if it's thowin a code?

 

Yes, I have checked to see if it would throw a code. So far every time I have checked nothing shows up. I brought it to my dealer a few months ago and they told me it was a crank shaft position sensor. I replaced this and the problem still persists.

 

Your fuel pump may be going bad. That could explain the rough cold starts and popping(starving). Doesn't need as much psi once warmed up. Use a fuel pressure tester and see what psi it's getting on a cold start. Wouldn't hurt to check the fuel filter too if that hasn't been replaced.

 

When you advance the key do you hear the fuel pump cycle??If it ends up being the pump, check the above sticky for a replacement...

 

My 05 700efi does the exact same thing! It has come on pretty fast. It just started a short time ago. No codes. I cleaned the t-bap and throttle body. I replaced the fuel filter, plugs, and wires. No luck. I removed the coil and cleaned it and the mount and hardware. This helped starting and idle but made it run worse under a load. So last night I ordered a new coil and the updated spacer. If this doesn't help I'll check the fuel pump. With as much time as my Popo spends in the mud and water its no suprise that it is running bad....

 

Well, I didn't have the starting problems, but when I got my 700 wet, it would sputter and not hardly rev up enough to move, so I blew out the spark plug boots, and I removed the plugs and cleaned them up and inspected the tips, and I then re assembled, and put a fair amount of die-electric grease, and the problem was gone for quite a while, and then it cam back when I pressure washed it with the side panels removed, and so I repeated the process and has been has been fine ever since

 

check to make sure the rubber throttle adapter tube is not cracked where it mounts to the engine. Mine was cracked/seperating from the steel mounting flange and did similar things.

 

Update:
I recieved my new coil and mount. To my suprise the new coil came with the spacer, bolt, and nut so I did not need to order those also. I installed the new parts and my problem was solved. No more hitting on one cylinder at start up. Then I took it for a spin. It ran just fine where as before it woldn't go more than 30mph. Hope this helps...

 

Glad you got it fixed.Thanks for the report...

John