Polaris Sportsman 500 HO won't start.

I keep a 2009 Polaris Sportsman 500 HO up at the farm. Since there was very little snow this winter, I used it on every visit up until January.

I tried to start the machine the first week of February and she wouldn’t start. The battery seemed a little low (it was cold) so I assumed the batter was getting weak and it was 3 years old anyway, so I figured a new battery would perk her right up.

Returned yesterday with a new battery and installed it. The machine cranks fine, but will not start.

Gas is full and non-ox is always used. On/Stop switch is “on”. Everything on the dash lights up properly. Nothing else has changed with the machine since it was parked last and was running.

With the choke “on” the machine will occasionally backfire when cranking, but not even a sputter to indicate that it’s close to starting.

Can anyone give me any ideas of anything else that might be the issue? It’s almost like a fuse has blown and cut off the ignition, but I have no idea where to look for such a fuse.

I REALLY want this machine to be working for turkey season. If I have to take it to the show, it’s going to be a major undertaking as the driveway is .5 miles of sloppy mess and I do not want to rut it up by driving in there right now to fetch the machine, so I will have to find another wheeler to tow the wheeler out to the main road, load, etc, the whole project will take half a day.

Please somebody give me an idea.

Many thanks.

Grouse

Grouse, can you dribble a little gas into the cylinder and see if it runs for a bit? That might tell you if it’s a fuel filter or carb problem. Another idea would be to pull the plug and hold it against ground while cranking it over to see if you’re getting any spark.

S.R.

The backfiring to me signals that its flooded. Hold the throttle wide open while turning it over and see if that helps. Nothing has found its way into your exhaust has it? I had a mouse make a damn nest in mine once and it wouldn’t start because of the back pressure.

My emergency switch went bad on mine. I could push down hard and wiggle the red run/stop switch and it would start. As soon as I took the pressure off it would shut off. Took it apart and lost most of the little springs and balls. Clean the little pins that plug into it also.

All good suggestions, thank you. Gives me a few more things to try before I haul it in.

Grouse

As suggested, pull the spark plug and clean it (is it wet)( do you have spark), pull air box cover and look for mice nest, then try to see if will run with a shot of ether in the carb.

Mine likes to eat spark plugs first thing I would do is change the plug.

Tom P. wrote:

Mine likes to eat spark plugs first thing I would do is change the plug.

Check the air cleaner and exhaust. Squirrels can use those areas for storage during the fall. I’ve seen them packed completely tight with corn and acorn chunks. This would effectively cause a flooding situation like you describe.

had a motorcycle act the same way, air box full of mouse living room, I was glad it didn’t start the filter was shredded.

Tom

tominblaine wrote:

had a motorcycle act the same way, air box full of mouse living room, I was glad it didn’t start the filter was shredded.

I did think to check that. Air filter needs changing, but no mouse had taken up residence.

I did not check the exhaust so that’s worth a look too, but I think the spark plug is more likely. I guess I never thought too much about the plug as it had been running fine, so then when it didn’t start, I just assumed it was the battery.

I did not have my spark tester at the farm, nor did I have a spare plug, so I didn’t even tear into that when I was there.

Many thanks for all the suggestions! I’ll report back.

Grouse

find the drain plug/screw on the carb,open it up and check for water,with temp swings and humidity the way its been condensation may have the lower part of the carb and tank full of water.
yes,it happens in below freezing temps.

I wont suggest this,just rambling about the days on the farm messing with old tractors.
when one wouldnt start,we would pull it down the road in a low gear so the motor would spin like a mother,amazing how big an arc an old magneto would throw when it was spun four times its design speed !!
often times we would see moisture,hickory nuts,acorns,fur,mouse parts and raw gas come out of the stack for half a mile then the old girl would start firing.
quite the sight to see fire billowing three feet out of the stack when it would finally light off !

Sheldon that was when you burned real gas. This corn crap they sell now we are lucky anything runs.

aint that the truth !! way back when gasoline was red,burned the helloutta ya without lighting it,smelled great,excellent parts washing solvent and would turn the stack a silvery white from the lead in it,glad the leads gone !!
if properly stored it would last a year or two,sigh,like that old racer said back in the day,gas is for washing parts,alcohol is for drinking,and nitro is for racing.
speaking of alky,,,,,,,glass is empty,be back in a minute.

Since my driveway is 1/2 mile long at the farm, it does not get plowed in the winter. Back in January, before we got a lot of snow, it occured to me I’d better do a fuel haul to get enough gas into the shed while I could still drive in. Lucky I did, by mid-Feb the driveway was blocked solid with snow and it won’t be driveable now until probably late April at best.

So I hauled in 3 cans of non-ox fresh from the pump that day. That’s what’s in the wheeler and that’s what I’ve been burning in my old gasser tractor all winter to keep the snow at bay around the camp.

I suppose it’s possible I got some super wet gas, but the tractor has been running off it just fine. I’ll bring my turkey baster and clear jar to pull a sample and see what it looks like.

Many thanks guys.

Grouse

Turkey Baster…..

I had to work on my power steering pump. The only way to “drain” the fluid of course is to suck it out. My wife says “How do you get the oil out of there?”. I said “with a turkey baster”. She said she didn’t have one. I reached in the tool box and pulled mine out. She almost fell over….”Why in the world would you have a turkey baster?????????”. Well, power steering fluid, putting water into batteries, who knows? I still laugh when I think about it.

S.R.

Steve Root wrote:

”Why in the world would you have a turkey baster?

Actually one of the handiest “mechanics” tools out there for the reasons you state. There are bigger, fancier, and more complex ways, but none is as portable and foolproof. I’ve even used it to extract water from a radiator when the drain petocock failed so I could strengthen the anti-freeze. Not ideal, but it worked.

The other cheap but indispensable tool I have is a very clear glass jar or old drinking glass. No idea where I got the one I use, but for some reason it’s very clear which is important. Put a sample of a fluid in the jar, hold it up to light and you can see all manner of contamination. Sediment, water, other foreign fluids, etc.

In fact for a long time I’ve been thinking of doing a “what does water in gas LOOK like” video that I could share.

Grouse

Here’s another one that’s handy….a glass measuring cup. It probably includes an “ounces” scale. Makes it very easy to measure two cycle oil. Found mine at a “dollar store” very cheap.

S.R.

I have a really good turkey baster story about a lesbian couple(quite attractive I might add) my wife knew for years, who confronted me one day soliciting some services for pregnancy. I was all for it until the baster was mentioned

True story.

OK, got up to the farm today with a fresh spark plug and other tools.

And the verdict is…

Fail. Epic fail. Changed the plug (and gapped the new one to .028), channged the air filter, drained the carb, tested the gas, charged the battery.

Nothing improved. Still cranks, backfires occasionally, but won’t even sputter.

Tried starting fluid shot straight in the carb throat. Even THAT won’t cause the engine to run for even a second.

Checked the plug and used a spark checker. There IS spark.

What in the heck could be wrong with this thing? If we get a below-freezing morning next week, I”m going to have to drag it down a half mile of sloppy wet driveway and get it to the shop. I’m out of ideas.

Grouse

Well for an internal engine to run, you need air, fuel, spark and timing. It sounds like you’ve looked at three out of the four. I have no idea how they do timing in that kind of an engine, sorry.

S.R.

tell me about the spark,good fat blue kernel with a distinct snap to it??
if not,same as no spark,if it is the least bit weak compression can blow the spark out.

timing,spark should occur just before top dead center,hold the wire near the plug and watch for the spark to occur as you hear the motor coming up on compression.
if the spark is erratic,something in the timing could be out of whack,module,trigger,chain/belt etc.

is the crankcase flooded with fuel?? if so,fumes can be drawn in from the crankcase breather vent causing an overly rich condition.
just to clarify,is it an after fire or back fire?? after fire is at the tail pipe,back fire is at the carb.

another thought,dang mice,look the wiring over good from the ignition box,fuse box,etc.
make sure non of the wires have been chewed on/shorted/open.
check all ground points,bad grounds on any type of ignition system can wreak havoc with spark timing.

Another thought is possibly the valve clearance? I did a little research and it seems the cam lobes on these tend to wear so it could be a possibility. It does have good compression though correct?

Check the spark frequency and color. It sounds like your spark is weak or inconsistat. Get a volt meter and a inline spark tester.

Grouse
If you have a good meter, test the continuity and OHMs on the coil & CDI. You’ll have to pull the parameters from the repair manual. I would still bet that you have a spark issue. The easiest/cheapest is the spark plugs as we all suggested. Next step is the coil putting out a weak charge.

OK, the shop called on Friday and here’s a new one for me at least.

The verdict: Sheared flywheel key. Flywheel key was broken and therefore the crank to flywheel position was off by about 20 degrees.

So that explains why I had spark and fuel but it still wouldn’t start.

Anyone ever heard of that one with a Polaris ATV? I’ve done dozens of flywheel keys on lawnmowers that hit stuff, but it never would have occurred to me on an ATV. Especially one that was running great when I drove it into the shed the last time I used it.

The mechanic said it happens occasionally, but didn’t offer anything on why now on this machine. Good news is the bill was $125 which I thought was very reasonable considering I was thinking this was a blown electronics brain box and I was expecting $500 or more.

Grouse

just read a couple of forums on polaris busting the keys,it is a common problem.
what is being done to help it quit doing it is turn the idle up a bit,from what I understand the belt drive and its components are heavy enough that they carry their shock load to the flywheel through the crankshaft at low idle speeds and will work on the key enough to eventually shear it.

one way to imagine what is going on is the crankshaft flexing enough that the flywheel is actually trying to change directions due to the harmonics imposed on it.

Polaris’s reliability isn’t their strong point.

Correction on the problem on my Polaris. It was a crankshaft key, not a flywheel key. They are two different parts.

I can’t find any reference online to this being a common issue with Polaris. I guess I’m just impressed the independent ATV repair shop closest to my farm was able to find the issue so quickly.

But of course, the part has to come directly from Polaris as the distribution places were all out. So it’s going to be another 3-5 day to get the part in and installed.

Just putting this out there in case somebody else has a similar “no start” issue.

Grouse