08 Dragon 700 rmk- won't stay running?

[AlaskanLuke]

I would really love some help with addressing this issue.

2008 Polaris Dragon 700 RMK 155.

I bought this as a second sled and the deal was to good to pass up. I immediately tore it down as it had 2,600 miles on it. I replaced the top end with weisco pistons and gasket kit, had a machine shop hone the cylinder slightly, installed v-force reeds, replaced exhaust bellows and springs, replaced the throttle body boot, new clutch weights and spring (SLP), new pipe and can (SLP), New HyperFax, found a broken LH throttle control with melted wires preventing lights from working... soldered it hard/direct to salvage.. seems fine. trying to explain all work incase of something simple or silly. I replaced the fuel filter, drained all oil and gas with a pump, replaced chain case gasket/oil and tightened, new plugs, new voltage regulator.
Upon completion of all this work, the sled fired strong and ran like a top. I did my three start and cool downs over the first 24 hours. I took it out and started my first ride and it started to bog when i punched it and noticed a light blinking once. Read on these threads it was a TPS, found that I missed plugging that wire back into the throttle bodies. Took it back out and no light and the sled ran like a fiery dragon. i put about four gallons of gas through it and took it to Haines, AK. i went through a couple more gallons on the flats and then took it for a big ride up into the mountains and started to attempt some full throttle sessions. it ran like a beast... upon my decent, halfway down in the trees, it just suddenly bogged and quit. I tried to start it, fired first pull and died. I pulled the plugs and changed them. let it cool for ten minutes. Pulled it and it fired and quit. pulled and pulled and pulled and nothing. Got towed down, unplugged all my wires and replugged. wiggled the fuel filter and injectors. pulled, it fired, and would barely idle. it would bog and die the second i touched the throttle. back in the shop now. upon checking all the wires again and shaking the fuel filter. it fires and seems to run fine, but bogs when i punch it. i can feather the gas and it will wind out. Anybody have any ideas what is going on here? plugged filter already? TPS? ECU? Grounding? It seems to have strong spark on both sides

 

[jman94]

Sounds like what happened to mine sort of... Check your Voltage regulator and ECU. My ECU was squishy in one corner where they normally completely burn through (i'll see if i can get pics tomorrow for ya). Caused by my VR burning out and overcharging it.

If I were you, i'd check the ECU and VR before they mess up your injectors and burn down the motor.

Edit: After re-reading your post, sounds nearly identical to what I encountered. I would bet that your ECU is toast.. sorry mate

 

[AlaskanLuke]

I replaced the voltage regulator. How does one diagnosis a bad ECU? Is there a way to test it? I have a suspicion that this sled has been sunk in a river due to a bad pond hopping. If i were to replace this ECU with a OEM part, will it need to be programmed?

 

[jman94]

I'm not exactly sure on the "test" procedure for the ecu. , but I'd take it off and look underneath, you'll see and smell if it's gotten hot. Also, if it was in the water then I'd make 100% sure all the wires are not corroded.

As for your VR, mine failed on the first run out and it was an aftermarket SPI, they covered my ecu though. It also could be just fine and your ecu is causing all the problems. And yes, usually it will need to be reflashed, some do come pre-flashed for 700's though.

I would also check the stator for corrosion if you think it has been completely underwater too. There's a thread on the Increasing IQ on how to test it, though I'd visually inspect it too.

It sucks when a rebuilt sled runs great then has electrical gremlins.. Hopefully this will help ya!

 

[MORSNO]

Sounds like the ECU and/or voltage regulator. Another thing to keep an eye on is those V Force reeds, they will not last long on a fuel injected sled. I'd put stock reeds back in the next time your in there.

 

[AlaskanLuke]

I see a ECU on ebay.. its 1/2 price from new. Kinda scary to do that, but.. I will take this one off today or tomorrow morning and update the smell and appearance. I have switched VR and the results are the same.

 

[Mag]

You can use a ecu off any other 700 sled that's been flashed for your same color injectors, might save you some dough if you can find somebody to swap with local.

 

[swade-o]

I am parting out a 2008 RMK 700 that had all latest updates, let me know if you need an ECU. THANKS!

 

[AlaskanLuke]

Update:

After many pulls and breaths, I have discovered a melted wire on the oil reservoir coming from the float sensor. I unplugged this and i fired right off Not exactly sure why it shorted out and melted, but i am excited that its not the ECU or something major. I will look into the wiring and try to track down the short.

 

[MORSNO]

Thanks for getting back with us and letting us know what you found and will repair.

 

[AlaskanLuke]

still haunted

Replaced the main wire harness and the headlight wire harness. replaced the oil float sensor. sled fired right off and ran for about three hours and then the headlight went out and the dash lights. it ran for a few minutes longer and died. once it cooled off completely it ran fine again. I am afraid to melt my new harness... any ideas why this is happening. I have already replaced the VR, did it kill this one already? Im afraid the ECU has had some damage, but nothing shows visible signs to that fact, it appears and smells ok. I have read about grounding the engine to the chassis, but can't find any pictures of this.. also need to check the stator?

 

[Hondaracer315]

Check the stator!!!!! Mine did the same thing stator took out the vr. Stator would run cold but once warm sled died.

 

[alaskanpower]

So what was the fix

 

[xlt man2]

So what was the fix

I would like to know too, old thread, but hard to track the issue.