Hi

I have a 2015 550 ESP efi.
Problem is only when I use the atv in the woods, with alot of idle and slow speed driving, and the temp is around 3 "stacks" on the temp gauge, and the fans kicks on and off.
Then it can start to "stutter", and when I try to apply throttle it wount go, and it backfires and the "injector" lamp starts to flash.
If I then leave it on idle it will start to stabilise, and I can drive it a bit longer, then it will start to do this again.

When on lower temps, its no problem.

Its still under warranty, and they have changed out this:

New fuel.
New CDI box
Looked for codes, found nothing.

But still problem.

To me it feels like fuel starve problem.
Cant it be vapour lock du to the fuellines be to close to the exhaust?

Any tips?

thanks

Are easily able to replicate the problem or is it intermittent? If you can I would suggest monitoring fuel pressure & the Narrow Band 02 sensor while it's acting up with the PDA

3 bars on the temp gauge is the normal operating range, fan will turn on between three & four.

My guess is a problem with the NB 02 sensor. It commands fuel in Closed Loop, it might be doing its job or it's giving wrong information.

[2015 Z Force 800 53/Trail EPS]

Generally speaking vapor-locking occurs when the fuel in the supply line reaches a temperature that it converts to gas or "boils" leaving the line charged with gas vapor. However, like water, the higher pressure the fluid is under, the higher temperature it will take to do this. In most cases the 40+ PSI that the EFI pump holds on the line is usually high enough to prevent this however there are known cases where a line is routed too close to an exhaust pipe that even this pressure isn't enough and in some cases fuels with ethanol will also still vaporize with heat it can receive in a contained area. Rare though... so like ctdls says, this is more likely heat-related, but effecting some other component such as an injector or O2 sensor's output. You can purchase some small pipe insulation wrap and wrap the fuel line as much as you can to see if that has an effect. Also, my brother's old 660 Yamaha Grizz does it all the time but it's carbureted, however he can remove the side covers to vent some heat buildup and it stops. You may be able to test by doing something similar. 

Are easily able to replicate the problem or is it intermittent? If you can I would suggest monitoring fuel pressure & the Narrow Band 02 sensor while it's acting up with the PDA

3 bars on the temp gauge is the normal operating range, fan will turn on between three & four.

My guess is a problem with the NB 02 sensor. It commands fuel in Closed Loop, it might be doing its job or it's giving wrong information.

Thanks!

Yes the results is the same. When hot ( 3-4 bars on the temp gauge ), it starts to "bang" from the exhaust, and it loose power when I try to accelerate, and the "efi" lamps starts to blink.
I dont think its the 02, as I can runt with no problem on the open road for as long as I whant. Its just when I drive slow in the forrest or plowing etc, and the motor gets a bit hotter this happens..

Generally speaking vapor-locking occurs when the fuel in the supply line reaches a temperature that it converts to gas or "boils" leaving the line charged with gas vapor. However, like water, the higher pressure the fluid is under, the higher temperature it will take to do this. In most cases the 40+ PSI that the EFI pump holds on the line is usually high enough to prevent this however there are known cases where a line is routed too close to an exhaust pipe that even this pressure isn't enough and in some cases fuels with ethanol will also still vaporize with heat it can receive in a contained area. Rare though... so like ctdls says, this is more likely heat-related, but effecting some other component such as an injector or O2 sensor's output. You can purchase some small pipe insulation wrap and wrap the fuel line as much as you can to see if that has an effect. Also, my brother's old 660 Yamaha Grizz does it all the time but it's carbureted, however he can remove the side covers to vent some heat buildup and it stops. You may be able to test by doing something similar.

Thanks for the reply.
I talked to CFMOTO in Sweden now, and they would like to try to swap out my fuel pump. According to them they seen this happend on some other models. WHen it get hot, the fuelpump cant manage to hold the pressure.
ALso in Sweden we have a crazy amount of e85 mixed in our regual fuel

You dealer needs to hook up a fuel pressure gauge & connect the PDA, get the thing hot & when it acts up they should easily identify the problem. My assumption is they have test equipment & know how to use it 

I hope it's the fuel pump, I highly doubt it however. Your fuel pump works harder when you are WOT & it needs fuel. Think of a fuel filter that's plugging, idles fine but when you are on the throttle it starts bogging & hesitating.

We have had some new out of the box units not want to idle initially. I think it's something to do with the fuel pressure regulator, it corrects itself after a few minutes & never returns. So we have never been able to troubleshoot properly, once again if this is what's happening with your ATV a fuel pressure gauge will show it.

If they keep replacing parts they should eventually fix it  hopefully you are patient 

Also, my brother's old 660 Yamaha Grizz does it all the time but it's carbureted, however he can remove the side covers to vent some heat buildup and it stops. You may be able to test by doing something similar.

Off topic but what you can tell your brother to do as I did with mine was drill 2 one inch holes in the plastic in between the seat and gas tank. That allows the heat and steam caught in that area to vent out and the carburetor to breath in fresh air.
Resolved my issue.

[2015 Z Force 800 53/Trail EPS]

Also, my brother's old 660 Yamaha Grizz does it all the time but it's carbureted, however he can remove the side covers to vent some heat buildup and it stops. You may be able to test by doing something similar.

Off topic but what you can tell your brother to do as I did with mine was drill 2 one inch holes in the plastic in between the seat and gas tank. That allows the heat and steam caught in that area to vent out and the carburetor to breath in fresh air.
Resolved my issue.

I will. Thanks.

Also, my brother's old 660 Yamaha Grizz does it all the time but it's carbureted, however he can remove the side covers to vent some heat buildup and it stops. You may be able to test by doing something similar.

Off topic but what you can tell your brother to do as I did with mine was drill 2 one inch holes in the plastic in between the seat and gas tank. That allows the heat and steam caught in that area to vent out and the carburetor to breath in fresh air.
Resolved my issue.

I will. Thanks.

Tell him to remove the seat and drill just shy of the seam and gap between the seat and tank cover (basically under the seat) so that is is aesthetically pleasing and out of sight. Still enough clearance there to allow for ventilation as the seat sits just a bit higher than the gas tank cover and allows for air flow.

Update.

Did some testing today.

I started to heatwrap the exhaust, and I also lifted the tankt, and put a heat protection "carpet" under the tank.
And then some alutape on the side, only to test:



This made it much much better.
Before I hade problem as soon as the temp meter was around 3-4 "bars" and during low speed in the forest etc.
Now I could drive like this, and every 5-10 minuts the EFI lamp would blink fast, and the motor hesitate, then get back to normal again. So big improvements.

I tore it down again.
And now I made the discovery that the ignition coil is very close to the exhaust. I know from working on cars, that ignition coils and heat is not friends.
I wraped the coil with some heat "carpet", and whent out again.



And not a single problem!
I pushed the ATV as I never hade before, just to build up more heat. But nothing, it just works!

Im now doing a new bracket to move the ignition coil to the other side of the frame. Away from the exhaust.
I now  moved it, and used a zipetie to fix it in place. But having it there also works, even without the head protection.



The retailer already swaped out the ignition coil twice during the fault search, under warranty. So this is not a bad coil, its the heat build up  apparently.

//Anders

[2015 Z Force 800 53/Trail EPS]

Good, Now you need to tell CFM about this so they can relocate the coil at the plant.

Good, Now you need to tell CFM about this so they can relocate the coil at the plant.

Yes. Will talk to them this week..

This is good information. Mine glitched out a couple times on me but never when running. I would be moving slowly under a load or pulling a trailer and when I shut it off it wouldn't restart. It would act like it was out of gas. I would pull the seat off and let it cool a bit then it was back to normal. Between this and the seat getting hot I decided to wrap the exhaust. The seat still gets hot in the summertime but I haven't had that starting issue again. I'll look at the coil next chance I have to see where it is, as mine is a 2016

I don't have much experience with this atv, but seems the newer polaris, canam and CFM all share a hot seat and leg problem. What works well for canam is boxing in the pipe with a heat shield. Might be something to look at.

I don't have much experience with this atv, but seems the newer polaris, canam and CFM all share a hot seat and leg problem. What works well for canam is boxing in the pipe with a heat shield. Might be something to look at.

I wrapped the pipe with header wrap from the head all the way to the muffler. But I agree something more should be done. I think part of the issue is all the plastic these things have. It just traps the heat in there.