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Discussion Starter #1
so my 2012 rzr900 with 3k miles has been running perfect, till yesterday, I drove it on to trailer, wet somewhere, drove off trailer, shut off, got ready to go, ten minutes later fire it up and pop pop pop backfiring and stall, wont start after that, what I found was wire out of tps for tps signal came out of connector, so I get it home repair connection, clean sooted spark plugs and o2 sensor from trying to start is so many times, it fires up with a little throttle runs good but wont idle, I can hold throttle at 1500 rpm and it runs, take foot off and dies, checked iac looks clean and moves in and out, anybody run into this before ? any ideas ???? no codes !!
 

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fuel pressure readings??
 

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Discussion Starter #4
Pump comes on and I have 40 lb's pressure, changed regulator and have the same pressure! Dont know what its supposed to be!
 

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Discussion Starter #7
now im finding out that 2011 and 12's used 40psi, and 2013 and up uses 58psi , but mine is MCX turboed, so im going to put pressure regulator and new fuel pump in and turn it up, see if that helps ! strange that it ran very well prior to this incident ! really don't know why it wont idle right now !
 

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Fuel pump doesn't make since because it will use less fuel at idle than when you push the throttle. My simple mind would be included to look at the throttle position sensor.
 

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the fact that's it's turbo'd would have been good information to use in your original post... that can change a number of things...

You said you investigated the IAC valve? Look into the service manual and verify you verified the appropriate things.

The popping before it died is very Interesting as well.... also judging by your previous posts about the MAQS not opening correctly, that is still very suspect to me... so @White Lightning 19 is very possibly correct in suspecting the TPS.


Fuel pump doesn't make since because it will use less fuel at idle than when you push the throttle. My simple mind would be included to look at the throttle position sensor.
Failing electric fuel pumps can do very strange things really, you have a lower current supply, and possibly voltage, at idle than you do at 7000 RPM... and with no diagnostic codes, fuel pressure is a good thing to investigate. The ECM takes fuel pressure for granted, so it won't immediately give a diagnostic code in relation to lower fuel pressure or inadequate fuel supply...something else has to cause the error first, and then most people will fix the effect, rather than the cause. I'm not saying it's the OP's issue, because it very well may not be, but it's still always a good thing to verify, his Turbo setup may need a fuel pressure different then stock tho, so it kinda makes it an unknown at this point.
 

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Discussion Starter #10
tps is working fine now, I found a wiring issue with the tps sensor output wire, repaired that and sensor is working correctly !! popping before it died due to lean situation, no tps at that time so lots of air little gas ! voltage is spot on so no issue there !
 

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Discussion Starter #12
ok here's were I am ! compression 160 PSI both pots, new fuel injectors, new spark plugs, changed IAC device, changed TPS, checked vacuum 10 to 15 inches of merc. , 40 PSI fuel pressure, it will idle for 10 to 20 seconds at 1250 RPM then die , this is a turboed engine ! it ran perfect till it back fired !!! it's got me swinging!!!!, I cant make it idle !! any idea's folks ????
 

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Discussion Starter #13
Oh and if you give it some throttle like 1400 RPM from there up it runs perfect !! at 1400 it will just keep running !
 

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Discussion Starter #14
I found I have 160 psi compression, and was told it should be 225-250 psi, is this correct ??
 

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Remember that compression numbers have to be adjusted for altitude. For example if you are at 4500 ft elevation you use .880. So 160/.880=182. You can lookup the elevation char for right divisor.
 

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My best guess would be an intake valve. Possibly a shim got dislodged as they just sit under the bucket on a 2012. I would do a leak down test. If it’s the intake valves you will hear it in the filter housing.

My valves were tight and I had to give it a small amount of throttle to start it and until it warmed up or it would die. After I adjusted the valve lash (by replacing shims) it starts perfectly now.
 

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Discussion Starter #17
well I said screw it and tore the engine down to rebuild anyway ! and found the idle problem !! one intake boot was ripped 2/3 's of the way around on the bottom side , so I couldn't see it till disassembly !
 
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