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Discussion Starter #1
In the cold weather this winter, the ATV started ... stumbled and then backfired.


Has not started since. Starter turns fine. No diagnostic on startup.

Has abt 120 hours. Original plug. Probably has a bad temperature sensor someplace. Had to replace the power distribution module at abt 50 hours. This problem is different.

Before I take it to the shop for what is likely to be an expensive repair ... where should I look first?

Thanks!
 

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I would pull your plug and make sure its not fouled or bridged. also if you can bring it somewhere warm or blow one of those torpedo heaters on it. It might be possible that somethings blocking the fuel line? Does the fuel pump run when you turn the key on?
 

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Start with the basics. For the engine to run you need fuel, air, spark, and compression. You need to narrow down the problem source.
When you crank the engine is there spark at the plug? Pull the plug. Is it dry or wet with fuel (or water)? Put it in the plug wire and lay the metal part of the plug against the engine. Crank the engine. You should get a strong blue/yellow spark across the plug gap.

When you turn the key on do you hear the fuel pump run for a couple seconds? If not did it blow a fuse? Have a bad connection? Did the fuel pump crap out? If you do hear it run, is fuel getting to the injection unit?
 

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Discussion Starter #4
Fuel pump runs after the key switch is used to turn the starter.

What is the magic way to get at the plug to remove it? Is in the most occluded area I've ever had to get a tool. Even working around headers has been easier!
 

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Should be a tool in your tool kit, take off side panels, blow out around s[park plug with compressed air, so any dirt doesn't fall into motor.
 

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Discussion Starter #6
OK ...

Tool kit has a handle and a tube with ends formed into light duty sockets. 5/8" socket end fits into the handle. Wrong end for the plug is available when the handle attached ... and the tube then appears to be too long anyway.

Must be missing something terribly obvious ... a little help please!

Don't have a 5/8" deep wobble socket. Do I need to go buy one?
 

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I found that a socket extension & a sparkplug socket would be the best bet.
 

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I have a 2008 HO EFI that I spent LOTS of time in the past week troubleshooting a intermitant just stop running issue, had to become an EFI expert in a week. Do you have spark and fuel pressure? DO you have the service manual for it? Most all the sensors all teh senors are easy to check with a good ohm meter. If you have a bad or disconnected sensor most likley check engine light will be on, short of crank positon and throttle position sensors it shoudl try to start in fail safe mode with any of the other sensors bad. Did you check for fault codes in ECU? Key to know first is if you have fuel pressue, 39 psi, and spark?
 

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Discussion Starter #9
Got it!

Needed to use a snap-on handle angle adjustable fine ratchet to get it out. Was easy then.


Plug looked OK but was a bit carboned up. Changed it anyway. ATV fired immediately.

Still needs to go to the shop to have the temp sensors checked.


THANKS GUYS!!!!
 

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Got it!

Needed to use a snap-on handle angle adjustable fine ratchet to get it out. Was easy then.


Plug looked OK but was a bit carboned up. Changed it anyway. ATV fired immediately.

Still needs to go to the shop to have the temp sensors checked.


THANKS GUYS!!!!
Good deal!!! If you have an Ohm meter you can check the sensors yourself in 10 minutes or less. The engine coolant temp sensor (ETS Sensor) on side of engine by left foot at room temp, 68 degrees F should be 37.3-39.2 Kilo Ohms and go down as temp increases, can be checked without removing, just unplug and take a reading off it. The air temp sensor (IAT Sensor)located in the air cleaner box same thing, unplug it and put Ohm meter on it, should ne 2.45 K Ohm +/- .36 k Ohm at 68 F. If your squeeze the little bulb end of it located inside air box between warm fingers the Ohm reading should go down pretty quickly. If you don;t have a service manual for it I highly suggest find if online and down load, if you want I can email you the 2008 manual if you PM me your email address, it should be pretty close
 

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PS, get some dielectric silcon paste and grease up the spark plug boot between the oring looking parts at the top to keep water out of the plug well, it gets wet VERY easy, I found out the hard way!! Do the coil end too while your at it. Check the relay sockets for EFI, Fule Pump, and Cooling fan located under the front cover below head light too, mine where teh source of my ills, corodded contacts on bottom of the relays, the bases are not water proof, grease them up too after you clean them
 

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Discussion Starter #12
Checked the sensors ... 79.4F

engine coolant sensor 31.4K Ohms
IAT 1667 Ohms

Neither seems in range. Any further tests that should be run?
 

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I might be a little lost. What makes you think that it needs a temp sensor?
 

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Discussion Starter #14
Is harder to start when cold, and it will not stay idling. Seems fine when the ambient temp is 70F or higher. Was not always that way!
 

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Its probably different on the EFI models but I know on the carbureted models if the throttle cable it too tight it just kind of sputters and dies when its cold out. I'm having that problem with mine, unfortunately that's not the solution in my case. IT screws with the throttle position sensor or something.
 

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Index of /ORV Manuals/Polaris/Sportsman/2007

Check that link, theres a 500 X2 service manual but it may apply to you as well, you could also go down a level and us the 08 manual too, in there will be troubleshooting steps for hard cold start
 

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Discussion Starter #17
A very light touch on the throttle seems to make it somewhat better save when it is very cold.

Is this the sort of thing that a decent Polaris shop can fix without charging me an arm and a leg?
 

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depends on what it ends up being, have you tried to bump up the throttle a little bit?
 

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Am I missing something, the quad is not firing or is firing? My bet would be the Key way on the flywheel sheared with the back fire. Guy I work with happened to his 2010 Sportsman 500 with only about 40 hours. You will get spark but not at the right timing to run if the flywheel is grabbing slightly but not enough cause the key is broken. Its a five dollar part, but you need a harmonic balancer puller to remove the flywheel to replace it. Can easily see it with the side cover off that says "Polaris" Right side of bike. Shoud be other write uops on this issue.
 

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Checked the sensors ... 79.4F

engine coolant sensor 31.4K Ohms
IAT 1667 Ohms

Neither seems in range. Any further tests that should be run?
When you tested the ETS was the engine running at any time in the hours before or was it sitting for hours in an area at a stable temp or did you remove the sensor and know the temp it was in was 79.4 degrees? The reading you got sounds like what it woudl be around 100 or so degrees F like an engine that was just running a few hours before. Either way shoudl not have effected idle to the point of making engine stall, IAC control valve should be trying to maintain idle at 1200 RPM not matter what the temp or engine load (ie lights on/off, cooling fan cycling, etc). The IAT at 1.667 k ohms sounds about correct for around 80 dgrees F, and again not that far out that it should not have effected idle enough to make engine die. HOw old is the fuel in the quad? Have you tried draining the tank dry and replacing fuel with fresh with 2 oz per gallon of Sea Foam in it? If you are really set it is the ETS or IAT sensor for a cheap test you can go to Radio Shack and get resistors to simulate 38k and 2.5 k Ohms and just stick there lead ends into the sensor plugs and fool the ECU into thinking ambient is 68 F and see how it starts and idles then, I htink it most likely will be no different.

Have you removed the filter box from the throttle body inlet and looked down it to see if the butterfly valve is dirty or not? That will effect idle, it can be cleaned with some spray throttle body cleaner just like a cars unit. Open the buttery fly with throttle lever, fold up a paper towel and slip it down the throat so you don't flood the piston with the solvent and spray the plate and scrub with an old tooth brush top and bottom so you don't have to spray half a can of the stuff in there to get the throat and plate clean. When putting the air box back on make sure the clamps front and rear of the throttle body are tight, leaks there will casue idle issues also.
 
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