I can tell you where I start
1. The throttle body gets coked up (carbon build up on the inside of the throttle body). Clean the throttle body with throttle body cleaner or carb cleaner sprays.
2. checking the TPS adjustment, miss adjusted TPS usually causes poor idling situations
3. check the fuel pressure. I believe it is 43 psi i will confirm it and get back to you
4. check the FI codes on Polaris's Digital Wrench
I do not know what your dealership has checked they may have done what I do and more. This is where I start and if all of this passes the tests i start to look at the FI and Ignition system.
The fuel pressure is 39 psi.
I had a 2007 Ranger crew today with the missing, popping after driving for about two miles. I did all of the test I described to you before. I did have a code 21 Lose of engine sycrnitation. Meaning the computer did not know what position the piston was in the cylinder. I checked the Crank Position Sensor CPS. used an ohm meter to test it found it had .586 ohms that was ok. checked the air gap between the flywheel and CPS that was ok. checked wiring to CPS from ECM no opens or shorts found. Still would not run correctly, until I disconnected the ECM from the wiring harness to check for corrosion in the connector. after reinstalling the ECM the unit has been running good. Went about six miles and no problem since. I do not know if the disconnecting and reconnecting reset something in the ECM..
Did you keep the Fuel pressure gage on when the engin was miss fireing?
you may have done this but i would check the fuel pressure when it is acting up. I had a ranger that would run ok at times then would start missing and popping. The fuel pump could not pump 39 psi consistently, sometimes it would and sometimes it couldn't keep it above 39psi. another thing is fuel volume could be a problem. you may have good fuel pressure and not enough volume to keep the unit running correctly.
How long did you disconnect the ECM for?
From what you are describing sounds like you have a injector going bad. As the unit warms up the injectors electrical resistance increases, and due to the higher resistance the injector will not open enough to allow the proper amount of fuel in to the engine. You can do a resistance test on the injectors to see if their is a bad one. the resistance should be close between the two if not you have one going bad. I will get you the resistance spec today.
The valve problem is possible. I would think that the valve is not sealing like with adjustable valves that are set to tight. It will start but when they warm up the valve will not close all the way due to the tight adjustment. they usually will not stay running when they warm up. I do not think it is a stuck valve as it would hit the piston and bend it. Then it would not start due to no compression. Have you taken a compression test?
it could be carbon build up on the valves. I would use Yamaha ring free to help get rid of carbon if that's what it is.
it is blind plug from left side of crankcase by the oil filter.
I know that two to three of the 700 & 800 EFI motors we had to replace the lifters due to them collapsing.
the oil pump should not need to be primed at this point. priming is only needed when the motor has been rebuilt. that priming passage is where you can take the oil pressure reading. if the valve has not seen oil in awhile you could have a blocked passage or a weak oil pump.
I think you are correct John.
That is the only way to test the oil pumps output. Other than remove the motor and split the cases and physically view the oil pump. sounds like you may have some sort of restriction in the intake to the oil pump. Like a clogged screen or plugged oil filter. I am going to check out the oil feed chart today and i will get back to you.
the clogged screen, oil filter is clogged or the oil pump has failed.
Ok Let me know what happens.
I Like the rangers for the twin cylinder motor. they are good work vehicles. Yes they do come short in quality and engineering department compared to the imports..
I agree that they should help you out. hope it turns out well for you