15 KTM 350 XCF-W, cutting out after 5 min, then backfiring. need help

Hower131
Posts
14
Joined
4/1/2008
Location
US
2015 KTM 350 XCF-w

Had the bike on the track today, it would do a couple laps and run great, then the bike would start to pop and cut out. Might even backfire hard a couple times before it totally died. Sounded almost like it was losing fuel as it would bog when I turned the throttle. Once the bike stalled, no electronics would function for 5 seconds, starter wouldn't turn, light wouldn't turn on.

After the 5 seconds was up, bike would fire but be under powered and prone to bogging and dying again.

Once the Bike would be totally cooled down, it would run great for 5 or so min and then repeat the issues.

Checked the Air Vent hose, fuel filter, no tank debris, plug cap was secured, oil levels good, filter box clean, all connections looked good around the bike. The Bike has also been run on VP t4 all 57 hours of it's entire life sans 1 gallon of gas once.

Drained the oil, no issues there either.

I have not checked the injector and the battery is a bit old and does need charged every week, but it had zero issues turning the motor over and over today.

Help please!
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Paw Paw 271
Posts
3639
Joined
4/3/2013
Location
Benton, LA US
3/26/2017 3:42am
If it still has the OEM battery, I would suggest it is in need of replacement. There could be other electrical issues causing it to drain.
I would suggest checking the voltage to the battery when running as it may not be charging correctly.

Paw Paw
BobPA
Posts
8323
Joined
10/31/2013
Location
PA US
3/26/2017 7:41am
Sounds like a stator issue to me
Rogerson207
Posts
104
Joined
1/21/2016
Location
Billings, MO US
3/26/2017 8:00am Edited Date/Time 3/26/2017 8:01am
I am not familiar with the set up on FI KTMs as I was back on Yamaha before KTM went FI on their bikes. However if they run a similar set up it could the be the IAP sensor on the throttle body. I have a buddy with a newer YZ450 that was doing the same kind of stuff. Luckily Yamaha has the tuner so I was able to get a code number and have an idea of where to start. Problem is the sensor data on the tuner appeared to change with manual pressure and vacuum applied to it with a syringe so I chased the problem in circles checking most of what was already mentioned in your thread. I got lucky and had my 12 YZ450 throttle body in a drawer on my bench, because my bike is torn for a full rebuild. Stuck the intake air pressure sensor out of my bike onto my buddy's and his bike has ran fine ever since. Not sure that is any help to you as I don't know how you could get the codes out of your KTM if it even has any (on my buddy's bike code would come and go so that makes it even harder). But if you could find a voltage reference or ohms reading for the sensors on the bike that would be a place I would start since you covered a lot of the other stuff to check already. You might do some asking or searching and see what other bikes use the same air pressure sensor as your bike and see if you can find anyone in your area with one of those bikes that would let you swap their sensor to your bike and see if that fixes the issue. May not hurt to try to test the tps or swap it out with another one if you can also because on the YZs it can cause some issues similar to these also.

PawPaw is on to something as usual also, I work on cars for a living and see this all the time (don't claim to be an expert but I do have some experience and like to help when I can). A bad battery or a vehicle with some kind of issue that drains the battery can cause all kinds of issues with the electronics. On certain vehicles it will make them run weird and kick on the CEL also and you'll be chasing miss fire codes, lean/rich codes for a while if you don't check voltage first. Our vehicles depend on certain voltages to certain sensors to get accurate readings in order for the vehicle to operate properly and if that is out of spec the computer goes crazy trying to compensate. Makes sense to me that our FI bikes could be the same way.
SpoSean
Posts
1
Joined
2/2/2019
Location
Liberty Lake, WA US
2/2/2019 11:01pm
Hower131 wrote:
2015 KTM 350 XCF-w Had the bike on the track today, it would do a couple laps and run great, then the bike would start to...
2015 KTM 350 XCF-w

Had the bike on the track today, it would do a couple laps and run great, then the bike would start to pop and cut out. Might even backfire hard a couple times before it totally died. Sounded almost like it was losing fuel as it would bog when I turned the throttle. Once the bike stalled, no electronics would function for 5 seconds, starter wouldn't turn, light wouldn't turn on.

After the 5 seconds was up, bike would fire but be under powered and prone to bogging and dying again.

Once the Bike would be totally cooled down, it would run great for 5 or so min and then repeat the issues.

Checked the Air Vent hose, fuel filter, no tank debris, plug cap was secured, oil levels good, filter box clean, all connections looked good around the bike. The Bike has also been run on VP t4 all 57 hours of it's entire life sans 1 gallon of gas once.

Drained the oil, no issues there either.

I have not checked the injector and the battery is a bit old and does need charged every week, but it had zero issues turning the motor over and over today.

Help please!
Hower131 What did you figure out on this, my 2014 just started doing the same thing. I checked valves, changed fuel pump, made sure no debris, can't figure it out. Thanks

The Shop

CarlinoJoeVideo
Posts
7518
Joined
11/30/2013
Location
Portland/Los Angeles, CA US
2/2/2019 11:29pm
I’d check these parts. Either find someone with the same bike or find a parts place that has a good return policy:
Stator
Ecu
Regulator
Condenser
Coil
2/3/2019 2:47pm Edited Date/Time 2/3/2019 2:48pm
Hower131 wrote:
2015 KTM 350 XCF-w Had the bike on the track today, it would do a couple laps and run great, then the bike would start to...
2015 KTM 350 XCF-w

Had the bike on the track today, it would do a couple laps and run great, then the bike would start to pop and cut out. Might even backfire hard a couple times before it totally died. Sounded almost like it was losing fuel as it would bog when I turned the throttle. Once the bike stalled, no electronics would function for 5 seconds, starter wouldn't turn, light wouldn't turn on.

After the 5 seconds was up, bike would fire but be under powered and prone to bogging and dying again.

Once the Bike would be totally cooled down, it would run great for 5 or so min and then repeat the issues.

Checked the Air Vent hose, fuel filter, no tank debris, plug cap was secured, oil levels good, filter box clean, all connections looked good around the bike. The Bike has also been run on VP t4 all 57 hours of it's entire life sans 1 gallon of gas once.

Drained the oil, no issues there either.

I have not checked the injector and the battery is a bit old and does need charged every week, but it had zero issues turning the motor over and over today.

Help please!
Had similar issues on an 08 crf450r... once warm, bike would die.. let it completely cool Id start right up running great for 3-5 min.. never ending cycle.
changed the ignition coil and it never died again.
1
sandman768
Posts
7950
Joined
3/21/2014
Location
Saratoga Springs, NY US
2/3/2019 3:17pm
Does that bike have more than 1 fuel filter?
Minico
Posts
2
Joined
8/23/2020
Location
Oxford, MI US
8/23/2020 2:23pm
Hower131 wrote:
2015 KTM 350 XCF-w Had the bike on the track today, it would do a couple laps and run great, then the bike would start to...
2015 KTM 350 XCF-w

Had the bike on the track today, it would do a couple laps and run great, then the bike would start to pop and cut out. Might even backfire hard a couple times before it totally died. Sounded almost like it was losing fuel as it would bog when I turned the throttle. Once the bike stalled, no electronics would function for 5 seconds, starter wouldn't turn, light wouldn't turn on.

After the 5 seconds was up, bike would fire but be under powered and prone to bogging and dying again.

Once the Bike would be totally cooled down, it would run great for 5 or so min and then repeat the issues.

Checked the Air Vent hose, fuel filter, no tank debris, plug cap was secured, oil levels good, filter box clean, all connections looked good around the bike. The Bike has also been run on VP t4 all 57 hours of it's entire life sans 1 gallon of gas once.

Drained the oil, no issues there either.

I have not checked the injector and the battery is a bit old and does need charged every week, but it had zero issues turning the motor over and over today.

Help please!
Hower131

I'm experiencing the exact same issue with the same bike as you.

Did you find and resolve the issue?
Paw Paw
Posts
679
Joined
12/24/2011
Location
Benton, LA US
8/23/2020 5:53pm
Do an ohms test on the coil. It could be breaking down when warm.
Also inspect the fuel pump and filter.
What about your battery?

Paw Paw
Minico
Posts
2
Joined
8/23/2020
Location
Oxford, MI US
8/24/2020 5:55am
I replaced the coil and the plug. I have a lithium battery that reads full charge. There's an push button indicator right on the battery.

I adjusted the idle screw.

I have yet to inspect the fuel pump. How can the fuel pump be tested?

I have yet to replace the fuel filter.

I appears to happen once it's warmed up. As first it runs fine ( a few minutes), then sputters, backfires and stalls.
Factor E
Posts
939
Joined
9/22/2011
Location
So Cal, CA US
8/24/2020 8:42am
Prob the stator
If the pump was going out sometimes the run time will be shorter overtime you start then
go out completely
Huskyboy95
Posts
59
Joined
6/9/2020
Location
Valley Center, CA US
8/24/2020 10:06am
Check your fuel pressure with the fuel pressure gauge, it should be 52 to 54 psi. My 350 acted out and kind of did the same thing would hesitate and die. The filter could be plugging up and/or the fuel pump is dying in acting erratic. The quickest thing to do is check fuel pressure and that will let you know if it’s up to specs or not. Good luck
Factor E
Posts
939
Joined
9/22/2011
Location
So Cal, CA US
8/24/2020 11:33am
Try running a direct ground from batt to front ground on frame
See how long it runs
Paw Paw
Posts
679
Joined
12/24/2011
Location
Benton, LA US
8/24/2020 3:14pm
Take time to pull the fuel pump to be sure the fuel supply line at the pump is not kinked. This was a known issue in 2015-2016 bikes of that make.

Paw Paw
Huskyboy95
Posts
59
Joined
6/9/2020
Location
Valley Center, CA US
8/24/2020 4:17pm

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