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Discussion Starter · #1 ·
Brand new head jug piston and rings New fuel pump, plugs, injectors, and all throttle body sensor harness fixed. Put a new oil pressure relief valve in. Battery is new and reading over 12.8 volts. No check engine light but machine still cranks over and won't fire. Small shot of ether fires right up and then dies. Can check compression or leak down due to fresh rebuild nothing is seated. Any help greatly appreciated. Leaning towards oil pressure the most being either to high due to nightmare getting old relief valve out.
 

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what engine //???????????????? JHC.............
 

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Old fuel ? I would still check the fuel pressure...

"Small shot of ether fires right up ".........................Sounds like a fuel problem to me ...
 

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Discussion Starter · #5 ·
Pressure is 43 when ignition on and stays put when cranking. What is recommended on fuel? Only been running 87 octane in it. And of u put a bit of fuel directly in cylinder it fires rite up. And it's same fuel that is in tank.
 

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Discussion Starter · #6 ·
Threw in a extra fuel pump assembly and fuel pressure running at 49 psi when ignition switch is turned and while cranking its at 58. I'm guessing I need to flash the ecu to match that pressure but plugs are soaked and I've checked spark and getting good spark bright in color.
 

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2008 Polaris Ranger 700 XP 4x4 EFI
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Fuel pressure spec is 45 +/- 2 psi. You seem to be a little over spec, and seem to be flooding it out. Who did the rebuild? is the engine correctly timed? Any codes?
 

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"Pressure is 43 "

This is correct for a 2012 800. 2013 was the first year for the 58 psi regulator which was to have been implemented to help with the constant vapor lock problem with the "to lean" 800 engines . The 2013 ECU had a new flash to implement the new 58 psi which also held the injectors open longer on start up to assist clearing the injectors . You are going to FLOOD the engine by shooting 58 psi to a 2012 800...
 

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Discussion Starter · #9 ·
So get ecu to dealer to have flashed to run the 58 psi. Dealer sold me entire sending unit. And didn't state any of that. Aswell rebuild done by local shop. Plus if timing is off on these motors I believes the motor would be done due to it is geared timing. So if it moved out of time it would've sheared the timing gears and wouldn't even turn over.
 

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"So get ecu to dealer to have flashed to run the 58 psi. Dealer sold me entire sending unit. And didn't state any of that. Aswell rebuild done by local shop. "

R, no idea what you are getting at ............... So you already reflashed ? :unsure: Dealer sold you the parts and didnt tell you about how it works ??? Nothing surprising there o_O

What is a "Aswell rebuild " ?

Agreed, the only way the timing could be off is if the sprockets were not aligned properly..:unsure:
 

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Discussion Starter · #11 ·
Ment to state rebuild was at a local shop. And no the ecu wasn't flashed for the new pump. Asked for the 12 ranger 800 pump assembly and they had one on shelf. Bought it and nothing was stated about the flash for ecu to new pressure. And I just finished checking timing and all timing marks are lined up on every gear.
 

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"while cranking its at 58 "

R, no 2012 Ranger 800 in existence will take 58 psi on the fuel injection without the proper program flashed into the ECU. .
The ECU determines the injection timing and duration in accordance with the PROPER FUEL PRESSURE. To little or to much fuel pressure and you will have a problem. Proper fuel pressure on any EFI system is critical.
 

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Good luck R. Most dealers will require you to bring the entire Ranger in... Call around first ..
 

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Discussion Starter · #17 ·
Got it flashed and still a no go. Will pop over to run for a split second then it dies out. Have to let it sit for about 10 to 15 min and it'll pop over again. Put new cps and cam sensor in. Every sensor on motor is now new. And just for the hell of it had a buddy with another ranger and swapped ecu. Still nothing and his had the upgraded pump and flashed ecu.
 

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I had one that was giving me fits too. You really need to check compression that might be your problem. No compression, not start.

if compression is good, I know you said it would run on ether, but try this.
Put some gasoline in a water bottle and put a small hole in the cap. Take off the air filter and spray some gas into the intake. Try to start it. If it starts and runs here its a fuel issue. Either fuel pressure or injectors not putting out gas.
If it don't run doing that make sure its firing at the plug. If its firing you have timing issues.
 

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Discussion Starter · #19 ·
Runs on fuel poured into cylinder aswell as the ether. Found out I only had 3 volts at injectors I hard wired them and now have twelve volts. Question on that I have a 12 volt reading on both wires at injector when one probe on wire and other on motor. But when crank it drops to 10 volts. But no matter what it always has twelve volts key on or off.
 

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Runs on fuel poured into cylinder aswell as the ether. Found out I only had 3 volts at injectors I hard wired them and now have twelve volts. Question on that I have a 12 volt reading on both wires at injector when one probe on wire and other on motor. But when crank it drops to 10 volts. But no matter what it always has twelve volts key on or off.
If you put 12v on the injector it will spray fuel. Its ok to test by pulsing 12v on it but if you leave it on continuously, it will damage the injector.
Since you are loosing voltage on BOTH injectors probably not a ground issue. Both injectors are fed voltage from the relay box. See if you can check the voltage on A8 (see attached pic from the service manual.). The RD/DB wire is where both injectors gets their power.
Rectangle Font Parallel Pattern Diagram
 
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