hello OPT,my 08 x2 500 efi has cranking issues..it will crank and go dead,try to give it throttle and it just pops back thru the breather and wamt run..i had a new fuel pump(@ 41psi),throttle body,pick up coil and had a valve seat replaced cause they done a leakdown test on it and it failed.there is no check engine light coming on either..it has been at the shop for over 4 months and mechanic said he has no idea what it could be!!! im beyond stumped also..do u have ANY advice that can help me??thank you

 

and fuel infector is spraying fine also

 

From what we went through more than likely it has a wiring problem on the tbap harness or connector.NOT usually a sensor problem itself. Especially if it pops back trying to crank,one of the common symptoms. Wires can be chaffed or have a bare spot or soft feeling wires can melt internally. Plus pins can pull back in the connectors which can cause intermittent or constant problems. Codes may or may not be thrown which makes it even harder to track down at times. Polaris offers harness repair kits that are junk. Look at the "sticky post" in the expert section on spilling the beans on 700/800 efi wiring problems. Applies to all efi atvs. From there Otb came about and offered better kits.https://otbpowersports.com/products/
One other place to check is the grommet under the tbap sensor.If it's cracked or damaged it can suck air and cause the same problems. Again the tbap and tps wiring harnesses were the most common problems. Also make sure you have the throttle adjusted correctly or the etc contacts can touch. Here's the grommet on the parts break down.Item #20.

 

thanks OPT.will check all my wiring

 

keep us updated as to what you find out..

 

will do bud

 

hey OPT,you are the man.it was the grommet under the tbap sensor..replaced it and seal up my airbox and it runs like a new one again..thanks for all your help and knowledge...

 

I've had several like this on the 500s where the grommet would split sucking air. Yes you have to have a good sealed air box also whether it's carb or efi for them to run right also. Glad it was a simple fix.