06' 900 mid throttle cutting out

biggsy90 · Feb 16, 2015

Here are the symptoms. Runs pretty good for about 10 min then progressively starts cutting out. Seems worse between 4,500 and 5800 rpm. 6000 and up is OK. WOT runs very strong. Sled is new to me and has 3600 miles. Motor has 1,000.
here's what I have done. Replaced intake boots, cleaned exhaust valves, replaced exhaust valve bellows and yellow springs. Tried plugging exhaust ports,replaced TPS. reset Tps multiple times. Tried champion and ngk plugs and all look good. Motion pro cable. Changed fuel filter.
fuel pressure was over 100, not sure if that's OK or not.
Reed valves look ok, but ordered some SPI anyway. Do they go bad without chips? There is oil on them, is that normal?
Haven't checked the Stator or flywheel yet cuz sounds like a pita.
I've spent lots of time and money on this and I'm still no closer to getting it running right.
any other ideas or what am I missing?
thanks
Bill

Fuse900 · Feb 17, 2015

Did you replace the TPS pigtail? There is a updated harness with better wires and connectors. Also, how are you adjusting the TPS? Are you using the Polaris tool? If you made your own (like I attempted to do) the resistor needs to be spot on - 5V output. Your meter needs to be excellent also (Fluke). I had similar symptoms and finally had my local dealer set the tps with their equipment and it fixed the problem. I'd start there.

biggsy90 · Feb 17, 2015

yeah saw some of your provious posts about that. I did replace the pigtail and no change. its not a factory polaris TPS setting tool, but measures spot on 5.00v. Seems to take me forever to get it to .710v, but got it there and set idle at .97 as I usually am above 9,000 feet. I dont have a polaris dealer near by, so last resort is I will take it to the dealer in Steamboat and have them set it. but with 2 different TPS and both, I think, set up correctly, just not sure if thats the problem. Still wondering if it could be something else.

Confusion 900 · Feb 17, 2015

I had a similar problem and realized the throttle cable had stretched causing the throttle safety switch to cut the engine out at low speeds, at mid or full throttle it worked fine. Maybe you just need to tighten your cable.

biggsy90 · Feb 18, 2015

Cable is new and seems like the switch is working OK.

I just cant figure this out. seems like it does it more after driving for 10 min or so. How do I check the stator? Ive seen the ohm values in the manual, but not sure where the plug is. Do i have to remove the tank?

biggsy90 · Feb 21, 2015

Update.

Changed exhaust temp probe or sensor. Took flywheel off and had lots of grime and oil, so cleaned it really well. magnets still locked in place. Stator had no broken wires.

Seems like it actually got worse. 2 feet of fresh snow n
And couldn't really take advantage of it.

Threw in the towel and took it to the steamboat dealer, who wasn't sure they could fix it due to all the probs with the 900s.

I even tried to replace the stator, but it's on back order until March 13th. Any other thoughts would be greatly appreciated.

SixtySevenGT · Feb 22, 2015

Fuel Pump Filter

I had a similiar bog on my 06.

I was doing some major parts swapping so I removed the Fuel tank and the Fuel Pump inside the Tank.

To my supprise there was a fuel Filter on the Return end of the Fuel system and it was plugged solid.

What this does is back all the fuel pressure back into the injectors.

At WOT it was pretty good, mid range sucked. I removed the internal filter and just replaced it with a piece of fuel line.

Runs great, much better mileage.

biggsy90 · Feb 22, 2015

So this plugged filter on the return line was in the tank? Guess maybe it could be flooding at anything but WOT. I will check that if dealer cant come up with anything. Thanks.

biggsy90 · Feb 25, 2015

Dealer couldnt find anything wrong and couldnt reproduce the problem. Usually takes about 10 min of riding before it happens.
I guess I will try changing the reeds this weekend and if that doesnt work wait until the stators are off back order. and check the fuel tank line.
Any other ideas. ive replaced just about everything except the stator and computer.

Thanks
Bill

keithn429 · Feb 27, 2015

I know this isn't what you are looking for, but I am having a similar problem on my 05 Fusion. Difference is, that I can ride it for about 50 miles before it starts to act up (meaning a low end bog, misfire, no desire to go unless WOT). If I let it sit and eat dinner, it runs fine after that, for quite a few miles again. If I just let it sit for 5 minutes, I can get another mile or two before it acts up. Something is getting warm and cutting out, for sure. At this point, I am leaning towards stator, but because stator wires are behind seat, it is hard to diagnose issue with voltmeter before it cools down and works correctly again. If I discover anything, I will post it to this thread. Please keep us updated with what you find!

410Fortune · Feb 27, 2015

voltage regulator?
Have you guys checked fuel psi when this happens?

I see in the first post the fuel rail pressure was over 100 psi, this is NOT okay, it should be within spec, 60psi I believe for the 900 but we better look it up

If the pressure at the rail is over 100 psi then the regulator is shot and the injectors cannot possibly spray correctly with 100 psi behind them in fact they would likely leak fuel at all times the pump is running

this right here:

the steamboat dealer, who wasn't sure they could fix it due to all the probs with the 900s

is total BS, the 900 is no different from any other CFi Polaris sled, you need a different dealer!

I rebuilt my flywheel/stator assembly , no parts needed to fix 90% of the time.

try bypassing throttle kill switch and see if it persists
you guys need to be checking fuel rail pressure for sure, this really seems like a fuel issue too much is just as bad as not enough, it must all be working properly

keithn429 · Feb 27, 2015

410, questions for ya if you have time to answer---what does rebuilding your stator entail that you don't need parts to do it? Also, wouldn't it seem like the fuel supply issue would exist more regularly, rather than waiting until sled has been running so long? Unless somehow it could build more or less pressure after a long period of running? Thanks 410 for shedding some light on this for us!

biggsy90 · Feb 27, 2015

Thanks 410. The service manager seemed like a reasonable guy. He said they usually end up costing too much money to fix. still a little fishy.

Also they could not hook it up to the computer. Couldnt give me a reason for it. Ever heard of that before.

had them test the fuel pressure and they got steady 125psi. Asked them if that was normal and they said yes! despite the manual saying 58 i believe. Seems like that would make it very rich execpt for maybe WOT.

They did say the TPS was off a little and thats all they really did. Will see what happens tomorrow, but I am very doubtful.

Looks like the fuel regulator is in the tank, is that right? babbits didnt have a price listed like it was not available.

thanks
Bill

keithn429 · Feb 27, 2015

if you look into fuel pressures from 05/06 on other forums, you will find this information from those that seem to know ...following is from http://www.snowest.com/forum/showthread.php?t=309122

"2006 pumps 8 Bar with PSI 116 4 INJECTERS
2005 pumps 4 Bar with PSI 58 2 INJECTERS
They may look the same but they're not"

Therefore, your injector pressure would be correct. But what really needs to be understood, is whether or not that pressure is changing after your 10+ minute run time. In my limited knowledge, I do not see why it would, but I am hoping someone on here could correct me on that if it is possible.

biggsy90 · Feb 27, 2015

Thanks for that info. Back to thinking its n intermittent electrical problem. Just still can't figure out why it idles fine and runs WOT fine. Some day I hope to have it solved without replacing everything:face-icon-small-sho

keithn429 · Feb 27, 2015

narrowing down problem

biggsy, I rode mine tonight for 30 miles in temperatures right around 0 degrees Fahrenheit before it started acting up (bogging when I put minimal throttle on it, but coming to life under WOT). So because I thought it was an electric problem that was occurring, I decided to cool the electrical components that I could get at with snow. Try this on your sled, and see what happens. I never shut the engine off to keep things hot, but took off the airbox and threw snow down (and plenty of it) on the capacitor (CDI), voltage regulator, and ECU (which are all in a cluster down there). Immediately, once the overheated part cooled, the problem corrected itself. What this did, was allow me to narrow down the problem to one of these three components. Try this and see if you have the same results. If not, at least you may be more confident that it is not one of these components on your sled that has gone bad!

410Fortune · Feb 28, 2015

interesting info about 05 & 06 fuel pressure!

The dealer did not have digital wrench or your sled would not communicate with their system?

rebuilding the stator for me was basically taking it all apart and clean all the crud off. Clean the rouge off the flywheel and JB welded the inner ring
Soldered some wires and re assembled. Gave everything a really close inspection. These stators are pretty much a solid state unit most issues that occur with them will probably show them selves with an inspection.

Pictures and details of this are in my build thread

The thinking is that the fuel pump is getting hot and dropping the supply pressure, so a mechanical fuel pressure gauge hooked up to the schrader valve on the fuel rail while the issue happens with determine if its fuel related or not (to the pump/regulator, etc) Similar to any EFI return style system.

voltage regulator may be the culprit here?
what does the dash voltage read when this happens? headlights flicker?

TriumphoverU · Feb 28, 2015

I'm not sure if this is your problem or not, but I'm going to throw a possible solution out there for you. Fuel injector.

The reason I'm thinking this is because I just fixed a low speed bog on my 06 Fusion that maybe by coincidence also occurred around 4500 rpm. The only difference is my sled was bogging below 4500 rpm, and I had a bad low speed fuel injector that I had to replace. For your issue, I would guess that one of your high speed injectors is starting to fail.

When my sled was cold, it would usually run good and idle good, but as it warmed up the low speed injector would start to have issues and I would have a bog. Once it got bad enough for me to diagnose it intermittently would only run on one cylinder. My theory is that the injectors switched from the low speed injectors to the high speed injectors right around 4400 rpm. Anything above 4400 my sled would perform perfectly because it was now running on the high speed injectors. So I pulled the motor, bought a used injector to replace the one I suspected to be bad. I then sent out the original 3 + the used one I purchased, to witchhunter.com to have them cleaned and tested. All came back cleaned, rebuilt, new O-rings, new seals, and a detailed report that showed both before and after results of the flow testing.

Just for reference, the service manual refers to the injectors as partial load and full load.

In my terms:

partial load = low speed = lower fuel injector on the fuel rail
full load = high speed = upper fuel injector on the fuel rail

good luck!

biggsy90 · Feb 28, 2015

Keithn429, just saw your post and now I'm back at the cabin. Still doing same thing. Today did it straight out of the parking lot. Dealer didn't solve it. Seems that over 6000RPM runs pretty good. Mine will continue to do it even if i shut it down for 20 min for lunch. Didn't try the snow thing, but will definitely try that next time out, unfortunately may be a few weeks. And I'm not so sure it is related to temp anymore. It's progressing.b
Let me know what you find on yours.

410, battery gauge on dash does not change and my buddies say headlight doesn't seem to change. Runs soooooo good at WOT, that I really don't think it is a fuel pressure issue, but I will check that as well.
And I had a buddy pick up the sled so still don't have an answer about the computer issue. Hopefully Tuesday.

Triumph, I worried you are right. My hope was to get through the season and then pull the motor and send in the injectors. Though my worst rpm range seems to be 5200 to 6000, but it does miss at lower rpm as well.

Plan at this point is to change exhaust springs to purple, running yellow now and replace reeds with SPI. Was going to do that tonight, but left them at home!:face-icon-small-sho. Then will check fuel pressure while riding and try cooling components.

Any other advice?

Side note, this thing kicks serious a$$, and smokes my buddies at WOT, so now I too am hooked. Is there a 12 step program to get away from the 900's":face-icon-small-win

guidoxpress · Feb 28, 2015

Plug ur exhaust valves. Leave the solenoid plugged in to the electrical connection (just relive the hose and plug valves) and see if this is part of ur issue

I'm leaning towards a fuel psi issue (u must have 116psi or it's wrong)
Make sure you don't have a kink in The fuel line under the fuel filter to injectors.
If u haven't visually inspected the fuel lines in the tank with the fuel pump OUT do this.

Other ideas would be stator, bad injector(s) or injector wiring problem. Like a pin in the harness pushed down.

If u want a spare Ecu to have on hand I have a few for sale. They are for an 06 700 but ur dealer can reflash it to the 900 no problem. Pm if interested.

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06' 900 mid throttle cutting out

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