[ITGuy]

Hi guys!  I'm new the forum so hello!  I have a 2016 CF500AU-6L with 80 miles on it.  After running it for 25-35 minutes and shutting it off, it will no start again for at least a few hours.

Here are the facts:
-I have gas
-Kill switch not on
-When turning the key I hear the fuel pump turn on then go off as normal.
-Fuses checked, all good.
-I have two units, exactly the same, only one is having the issue.
-Unit cranks, but will not turn over.
-After the unit cools, it starts no issue.

As expected, I brought it to the dealer.  "No issue found."

I took a video that I'll show them but as I'm sure you all know, they'll say something like "oh well we can't replicate it so sorry"

Any help or ideas would be greatly appreciated.

[Cosmosdan]

I'm leaning towards vapor lock. Check where the fuel lines are and see if they are too close to the hot stuff.

[viejoperro]

Hello welcome, when was you ATV born?, manufacture date?, there is a service bulletin addressing an issue about hard starting when hot for a small amount of 2015 models,
In which the camshaft decompressor may be the cause, not releasing the valves after the engine is hot affecting the start, it always open the valve as it would be in a cold start.
Since your model is 2016 it should be corrected?, how often does this happen?, and it is always the same sintoms and issues? Please upload a video if possible. Is your dealer close?, do you have some mechanic knowledge?

[Cosmosdan]

Will it keep running fine once started?

[ITGuy]

Hi all, thanks for the replies!

@Cosmosdan - I'll take a look.  This was my original though as well but I looked at my identical unit, and everything looks like it's in the exact same spots.  I'll keep checking.  Also, once it starts again - it runs like a champ.  Until you ride it hard again - slow and over rough terrain - and shut it off.

@viejoperro - Not sure of the manufacture date, I'll try to look that up and get back here.  This issue doesn't happen all the time, but often enough to make it a concern.  As noted the unit has 80 miles on it...I'm afraid to bring it anywhere remote where it can't be towed back.  Dealer is about 25 minutes away.  I've had some buddies take a look at it who are Skidoo mechanics, and they can't figure anything out.  It sounds and looks like it's getting everything it needs - spark, fuel, power...we just haven't taken any tools to it - (I'm hoping the dealer did that)

I've attached a video...notice the temp gauge - shows cool but still won't start - this is after about a 45 minute rest period.  I know you can't hear it, but the fuel pump does turn on in this video.  Today, it took just under 90 minutes to start again - it's getting cooler here so I'm guessing that helps.

Video -

[Cosmosdan]

If it stays running than vapor lock might be out. I might lean to the decomp. issue then. I will see if I can find the TSB for that. I'm not sure how heat would affect the decomp, but I haven't seen them all yet so who knows. maybe something is too tight and it binds the weights so they don't fly out? I have just removed them on other machines to avoid issues later. Works the starter harder but that's cheaper than engine work.

[Wheels]

Next time it fails please try to unplug the start relay under the seat, we are STILL trying to find what is happening. Disconnect the harness from relay, reconnect and should fire and be ready to go.

[Wheels]

This problem effects the 3.0 ecu system, and has been found also in the 150nk motorbikes. You can try turning off the unit with the handlebar kill not the key switch. This seems to keep the problem from happening. I hope to have a solution to this problem by end of the week.

[Cosmosdan]

Here is the tsb

I would use loctite retaining compound 641? (red, not thredlock) if I found the pin sticking out. Clean the hole and pin with acetone before gluing.

[viejoperro]

Here is also the vin identification link, build year, model id.

[Wheels]

That the is for a cold start, he is having the classic hot start. I have found the cause today and will be working with the factory over the next couple weeks to get a fix out.

[viejoperro]

Ok the SB addresses starting in cold and restarting in hot after switched it off?, but if you found the cause can you share more information with us to now a little more about this issues?

[ITGuy]

Thanks everyone for helping me out with this.  It's such a pain - I'll give the kill switch a try instead of the key to turn it off.

@Wheels - I appreciate you looking into it.  Let me know if you need anything from me.

[Oxo888]

Any update on this issue? Same thing  just happened to me yesterday. I was running around 40kph when suddenly the throttle seems to choke and gradually loses power until the engine stop. I tried starting the engine again but it won't start. then i noticed that coolant was coming out of the overflow hose. I opened the gas tank and found out that the gasoline seems to be boiling as it was bubbling. Then after about 30 minutes I tried to start the engine again and after a few crank, I was able to run it again and everything was back to normal till I reached home. Any ideas? thanks!

[Cosmosdan]

They don't like hot fuel. You will need to relocate the fuel lines and add heat shield where you think it is getting too hot. Keep the fuel cool and I think your problem will go away.