2010 rzr 800.
This unit has severe lean fuel symptoms. Wont rev up, popping through intake, and stalling. Fuel pressure is 42 lbs constant. New injectors have been installed due to one failing. I have checked all intake connections for leaks and cannot find any. I have no diagnostic codes at all.
I had just rebuilt the top end and while I was warming the engine for the first time it was running great then this started. I have visually inspected all connectors and wiring through out the harness and reassembled with dielectric grease to insure good connection. I am currently waiting on my otb scanner to arrive so that I can see whats going on with the ecu and Im wondering if the ecu might have failed when this problem started.

 

Most of the problems like this can be sensor harness related,not the sensors or even the ecu. Like the manuals say 80% of efi problems are wiring related. Like in the parts breakdown there are several "harness repair kits" mentioned. Tbap wiring or the connector being the most common,tps wiring,crank sensor harness,etc. Codes may or may not be thrown.https://www.partzilla.com/catalog/po...-eps-r10vy76az Sometimes pins pull back from the connectors or soft feeling wires may have melted internally.A lot of times even Digital Wrench can't even catch intermittent or constant wiring problems. The Polaris repair kits are junk as I've replaced plenty of them olny to have to replace them again. Look under the Polaris expert section at the "sticky post" on 700/800 efi problems. These posts led to a better place for harness repair kits. https://otbpowersports.com/products/

 

i completely agree with you. Im very familiar with wiring problems connector issues ect. As many times as ive searched i just cant find anything out of the ordinary. Ive even used tester to check the pins and terminals in the connectors. I normally just get wire and the proper connectors and make my own repair harness and solder it to the harness. I just dont trust wire connectors. Ill keep looking though i know theres a problem somewhere i just havent located it yet. I guess it has come to removing all the wire loom and checking ever inch of the harness.

 

May be wrong but the popping back,erratic idle was usually from the t bap harness. Had to replace plenty of them on the 500,700 and 800 efi machines to cure that.Rarely had a tps harness,air temp or cps harness problem,but can happen.

 

I will recheck everything this weekend. I found another rzr to put my ecu on to see if it could be bad. Im a automotive tech and to me it just seems tps or tbap related not allowing the ecu to change injector output and timing. I wish the polaris shop manual was more in depth checking sensors and circuits with an ohm meter. It seems polaris relies on the digital wrench a lot.

 

Tried my ecm on another rzr and it ran fine.
Checked all the sensor wiring and found nothing
Got my otb powersports check tech a couple days ago and connected but theres evidently a communication problem.
Today I removed the floor pan and checked the harness all the way to the front of the machine and into the speedo I thought for sure there would be a bad wire somewhere but everything looks good. Not even thin wire insulation that I can find. I will say Im stumped on this one. Should I try a TBAP sensor just for the symptoms its having?

 

Popping back and stalling was in most cases caused by the t-bap harness or connector from our experience at the shop. Yes I'd try that first. You ruled out the ecm since it runs fine on another machine. Also check the crank position sensor and its wiring. Had a couple that rubbed small sections off the sheathing and would run erratic and ground out the spark if it touched the starter or engine case. I just repaired these and zip tied the harness away from the engine. That was mainly on the 700 and 800 atvs.May be routed a little different on the Rzr.

 

Update....Its been a while since ive had a chance to work on my Rzr cold weather no heat in the garage holidays ect. Anyway I changed the Tmap sensor its still the same. Ive also went through the wiring from front to back looking for bad places in the wiring and Ive tested tested the tps throught the harness and it appears to be working. Both injectors are spraying and both plugs have good arc on them. Im lost on this one theres no intake leakage it idles pretty much like it always did I think Ill pull the valve cover and check to make sure nothing is bent or broken for some reason. If I dont find something there I will just have to start checking wires from end to end with an ohm meter to make extra sure I didnt miss anything. when and if I find this problem Ill leave an update to let everyone know what the problem is.

 

Replaced the tbap sensor itself or the repair harness from Otb? Even on the tps sensor you may have continuity on the wiring up to the connector pins,but the pins themselves can pull back a little in these cheap connectors and not make good contact with the sensors.I've found that to happen also.Otb has both harness repair kits as it could be either one. Also where the tbap and tps sensor wiring tie into the main harness,I've found wiring problems there. Does involve having to strip the loom and going deeper into the harness.

 

i replaced the sensor. The connection is good. I pulled the valve cover to just check for a bent pushrod or something what I found was something that resembled a shop rag all ground up stuck to the top of the valve cover. I started it and the top end doesnt look like its oiling. I hate to say it but I think I might have left a rag in this thing between the rods when I was putting the pistons on the rods. well now im pretty concerned so I think Ill pull the oil filter and check it to start. Im guessing if its packed with the same thing I need to pull the engine out and split the case to clean it.