Hi all,

Bought a used 2007 sportsman 700 EFI about 2 years ago and ever since I had it, it has been producing the same problem but getting worse over time. I have tried everything i can think of to resolve it. The quad used to generally start up fine but if i let it get too warm and idle then it would start to sputter and feel like a misfire. I would shut it off and sometimes it would start right back up and other times i would have to restart a few more times. Replaced the radiator fan initially because i took it through some deeper mud it didn't like and the bearing was trashed. Bled and refilled the whole radiator/ coolant system. this was 2 years ago. no over heating issues since and fan cycles on and off normally.

Recently, it has gotten to the point that it starts but idles at roughly 800- 900 rpm before it stalls. if i feather the gas i can get it to creep forward but it will backfire through the airbox. This back fire is strong enough to push the clips holding the airbox down off (sounds like a gun shot). I began to mess with the TPS, after a long line of other repair attempts, and with the new TPS it idles at 1400-1500. I put the old sensor back in and was able to back probe it to .710 at idle and 3.56 at full throttle. No issues with old TPS or wiring ( i replaced harness 2 days ago). The new one does not have enough adjustment.

I'm out of ideas, below is all the things I tried and any results. I have looked at so many threads where people seem to have this same issue but it seems they solve them as they stop coming back to the threads. I even followed AKstew's post about EFI breakdown and how the EFI's work to try and trouble shoot.

A few things I noticed that seem to have no explanation:

1. The y pipe coming out of the exhaust manifold glows cherry red under mild riding. Flat even dirt road going about 35 mph. I have replaced exhaust donuts three times just in the front as it burns through them and begins to rattle. I've had to wrap the exhaust due to how hot this gets. some threads say this is normal some say it isn't. who knows anymore.
2. The RPMs seem to be wildly inaccurate as it will tell me that they are 1800RPM at full throttle going 50 mph and 3600RPM once i let off the gas ( i ordered a new crank position sensor because i love guessing and throwing parts at this thing)
3. the stutter/ stall/ misfire will occur off a cold engine or warm, dry or wet. it happens randomly going up hill or normal idle or just cruising around. No rhyme or reason to when it happens.
4. I have gotten the following codes but I'm sure some are caused by me by doing weird things to it to try and replicate the issues that happen with it such as pulling spark plug boots while it runs and pulling tps and tbap while running. 45,21,51,52,25.
5. After TPS and Tbap (sensor and harness) and sparkplug replacement yesterday. i unplugged battery to clear codes, after a few start attempts i got. 22,21,51,52.

What I have done so far:

1. Replaced spark plugs- small improvement for a short time, back to normal after one ride. Spark plug boots are a little worn but seem fine. I have unplugged while running and checked for spark and there is a very strong spark from both sides. Since it runs so hot i imagine the air/ fuel ratio is off but i found a thread that this was done to keep mpg higher. Plugs looked black when i replaced them yesterday.
2. Replaced fuel pump, fuel filter, replaced gas, lined bottom of tank with reflective heat foil- no noticed improvement, fuel pressure is fine. Did this thinking it was a heat issue i read about. I also ran Seafoam a few times to clean out injectors.
3. Replaced TPS and TPS wiring harness. If anything this just caused a new problem. The new one could not adjust to .710volts at idle. I put the old one back in with new soldered connections on the new harness and the voltage seems fine from idle to full throttle .710 to 3.56 volts. I unplugged this entirely at one point and the bike idled fine but wouldn't rev past 2500 RPM. I couldn't repeat this though. Followed wiring all the way back to ECU no breaks.
4. Replaced the Tbap and wiring harness. I can unplug this thing and it seems to make no difference. It made no change once i replaced it. i followed the wiring harness all the way back to ECU, no breaks in the wiring. Replaced the rubber intake boot at the same time with no improvement.
5. Battery was replaced and voltage is fine when off and when running normally. 12.5 to 14.5 when charging so i think the stator and coils are fine.
6. I checked the fuel injectors and find about 7 volts directly to the injectors. Harness is okay and no bare spots.

My last attempt (for now) will be to try the crank position sensor and hope this solves it. If you have any ideas, I feel like I am running out of things to do to this thing. I just want it to run. Of course it finally goes when hunting season is in mid swing. I can't even find a Polaris tech to look at it because of it's age. Any help is appreciated.

My buddy has a 2007 500 EFI HO that has similar issues. We adjusted his TPS yesterday as well and it made a slight improvement but there are moments when it feels like it's going to bog as well.

 

I would check compression with them running that lean they hay have cooked a ring or 2 and check your timing and valve adjustments

 

I have a CPS on the way if that doesn't fix it i will look into doing that type of stuff. I'm wary of opening the engine up to check those items. Is there a way to check valve adjustment and timing without opening the engine. do you know what the compression should be?