Here's the EFI troubleshooting page from the service manual

Efi Troubleshooting - Polaris Ranger RZR 800 Manual [Page 151]

Polaris Ranger RZR 800 Manual Online: Efi Troubleshooting. Fuel Starvation / Lean Mixture Symptoms: Hard start or no start, bog, backfire, popping through intake / exhaust, hesitation, detonation, low power, spark plug erosion, engine runs hot, surging, high idle, idle speed erratic. •...

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Symptoms: Hard start or no start, bog, backfire, popping

through intake / exhaust, hesitation, detonation, low power,

spark plug erosion, engine runs hot, surging, high idle, idle

speed erratic.

• No fuel in tank

• Restricted tank vent, or routed improperly

• Fuel lines or fuel injectors restricted

• Fuel filter plugged

• Fuel pump inoperative

• Air leak in system

• Intake air leak (throttle shaft, intake ducts, airbox or air cleaner cover)

• Incorrect throttle stop screw adjustment

Good place to start your search. What do your plugs look like ?? Nice tan color, or black or white.. Can tell you a lot..

 

Start with checking fuel pressure, I know you swapped pumps, but chech it anyhow, should be 40psi to 45 psi. Check compression, low compression can and will cause same issues, anything below 165psi you need a rebuild. Also check the oil pressure relief valve, if it is sticking intermittently then it can cause same issues. Search here on the forum pleanty of info for that. After that inspect and clean clutches, then go to electronics.

 

Thanks for the help! I’ll do some more looking and see what I can find. I did some additional testing—lifted the back end with a jack, and with the rear tires off the ground, I was able to get the machine to show 50 mph. Would it be bad to remove the belt and run the motor without it? I’m curious if the engine would be more responsive that way and help determine if the issue is with the belt or clutches.

 

I’m curious if the engine would be more responsive that way and help determine if the issue is with the belt or clutches.

Well, it likely wouldn't hurt anything, but why ?? It's not going to show ya anything ya don't already know.. It certainly isn't going to point you in any direction, and won't prove clutching is either good or bad.. The Drive clutch would be the one causing problems if your problem is clutching, but we haven't ruled out any of the simpler problems yet, so I'd start there first..

Snipped from Clothier's earlier post
Start with checking fuel pressure, I know you swapped pumps, but check it anyhow, should be 40psi to 45 psi. Check compression, low compression can and will cause same issues, anything below 165psi you need a rebuild.

Start with the basics, jumping to conclusions rarely solves anything. What made you think clutching if you don't mind me asking..

 

I checked compression and had about 170 psi in each. Fuel pump tested good. Spark plugs do look older, but they did have a tan color to them, I’ll probably replace them to be safe. I removed the injectors and cranked it over and they seemed to have a good spray. Currently trying to check the oil pressure relief valve.

 

I assume it isn't showing any codes on the instrument cluster? Check engine light isn't on? Another thing I rarely think of mentioning because it is very rare to happen, but you could check for a clogged exhaust. Also clogged intake. I would definitely pull the air filter and shine a light up into the intake tract and see if the throttle body is dirty or clean. Maybe even take a pic and post it here for us to see. Again after the mechanic stuff then I would start looking at electronics, tps mainly. They can be a pia to adjust, and I wouldn't touch it until you research adjusting a bit. They are finicky to say the least.

 

I was able to get the oil pressure relief valve out without any issue. I think I’m going to empty the fuel tank and put in new gas. This is with the air filter removed.

 

I was able to get the oil pressure relief valve out without any issue. I think I’m going to empty the fuel tank and put in new gas. This is with the air filter removed.
View attachment 769094

That doesn't look terrible. Fairly clean. At least maybe the engine hasn't ate alot of dust. New gas surely won't hurt. Just keep checking things off the list and you will eventually find the issue.

 

One other mechanical thing you might consider, is pulling the valve cover and checking to see how far the valves are opening. A worn cam would likely keep it from revving also. And the 800's are known for eating cams if the wrong oils are used.

 

I emptied and put new fuel in and also changed the spark plugs. It’s back to running like a champ! Now, I wish I would have tested after changing the spark plugs, before the fuel.

Thanks for the help!

 

I emptied and put new fuel in and also changed the spark plugs. It’s back to running like a champ! Now, I wish I would have tested after changing the spark plugs, before the fuel.

Thanks for the help!

Glad you got it running correctly! Bad fuel would be my guess though.