2017 KTM 350 wont idle

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8/6/2018 7:34 PM

Problem started the last time I rode. I made 2 1/2 laps, just enough to get the bike up to temp and heat saturated. Bike was running perfectly, just as it always has. Came into a corner 3rd gear fairly hot, as soon as I pull in the clutch and get on the brakes the bike died. I coast off to the side to get out of the way and go to restart, press the button and it doesn't want to start. It would fire but wouldn't stay started. Keep trying for a minute and it will finally start with just a little input from the throttle, let off the throttle and it immediately stalls.
I get it going and ride it back to my truck like this and let it sit for a few to cool off and think it over.
Start the bike back up and it fires right up and idles but it misses every couple of seconds, then after about 20 seconds it stalls again. Try again and it will stay running with just a little twist of the throttle and still a miss here and there, let off and it stalls. It gets worse the hotter the bike gets.
This was the Saturday before Loretta's and I didn't have time to mess with it before we left. So today I start digging into it.
Pulled the fuel filter at the quick disconnect out completely, no change.
Pulled out the fuel pump and checked that the line wasn't kinked. It looked great.
Checked that the fuel pump was kicking on and running, it seems fine and there appears to be no issue with the relay.
Checked the fuse and it was good
Checked the stator and it reads within spec according to the manual
Checked the coil and it's within spec
Checked the spark plug cap and it's within spec

It seems to be a weak spark or losing spark, but everything checks out fine. I also sanded the contact points on the frame and the coil to ensure it had a solid ground. I haven't checked the spark plug, I'll get a new on tomorrow and put it in.
I don't think it's a fuel issue, but could be wrong. If it were fuel, I'd expect it to stall at any RPM and not just at idle. I would check fuel pressure but don't have a way to do so, I'll have to bring it somewhere for that.

Anyone have any ideas or suggestions?

Thanks

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8/6/2018 10:29 PM

I’ve heard the spark plug cap can crack when removing and installing it. Then it sparks on the cylinder.
Check in this area
Photo

If that is it, I’d try someone else ECU and make sure the TPS is set correct.

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8/7/2018 1:36 AM

did you do an ohm test on your stator or did you do a voltage output test on it? My bets are on a faulty stator or rectifier. Stators can still be bad with good ohms readings.

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8/7/2018 2:27 PM

kb228 wrote:

did you do an ohm test on your stator or did you do a voltage output test on it? My bets are on a faulty stator or rectifier. Stators can still be bad with good ohms readings.

I did test resistance on the stator. I can check voltage, but the manual doesn't tell me what the output voltage should be so I won't know if it's good or not unless I'm getting nothing out.

I have a set of fuel filters and a new spark plug cap on the way, I'll get those changed later this week and see what happens.

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8/7/2018 4:08 PM

Checked the voltage output from the stator and I'm getting 15.8 volts out of it. The voltage stays steady even when the bike is missing and doesn't drop off until it dies. I don't know what the voltage should be, but the fact that the voltage doesn't fluctuate once the bike starts cutting out leads me to believe the stator is working correctly.

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8/7/2018 4:28 PM

Tps out of adjustment maybe?

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8/7/2018 5:14 PM

Did you do a load test on the battery? Whats your battery voltage while running? To me it sounds like the bike isnt producing enough power at low rpm and fixes itself at higher rpm. Also take a gander at the regulator/rectifier.

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8/7/2018 5:50 PM

yz133rider wrote:

Tps out of adjustment maybe?

I'm checking the TPS now to see what it's set at. It doesn't make a difference if it's plugged in or not though. I unplug it while the bike is running and there's no change.

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8/7/2018 6:15 PM

kb228 wrote:

Did you do a load test on the battery? Whats your battery voltage while running? To me it sounds like the bike isnt producing enough power at low rpm and fixes itself at higher rpm. Also take a gander at the regulator/rectifier.

Yes.

Battery voltage sits at 13.3V, it drops to around 9V under load. While the bike is running it's at 13.5V. Disconnect the battery and check the voltage on the cables and I'm at 14.1V coming from the rectifier.

I'm struggling with the TPS. My understanding is that I should be getting around .5V at idle. However, I'm getting the full 5V across the 2 outside pins. Maybe the TPS is bad?

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8/7/2018 6:40 PM

Finally got a good measurement on the TPS, it's set at .586V. According to what I'm reading, that should be good though some people do adjust it a little higher. I'm hesitant to make an adjustment to it because I could dig myself into a hole and make a problem worse. I'm not convinced that the TPS is the issue.
I'm stuck on the in tank fuel filter being the issue but won't know until I get the new one in. I didn't think it was a fuel issue at first but now I'm leaning/hoping that's what it is. Either way, I need to get this thing running.

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8/7/2018 6:40 PM

Did you check the plug cap for cracks? All the grounds around the coil tight and on metal not paint?

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8/7/2018 6:59 PM

CarlinoJoeVideo wrote:

Did you check the plug cap for cracks? All the grounds around the coil tight and on metal not paint?

Yes, I checked it and didn't see any. I have a new one ordered and will replace it when it arrives. Grounds have all been cleaned and checked.

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8/7/2018 7:28 PM
Edited Date/Time: 8/7/2018 7:29 PM

Probably the previous owner! lol

Maybe water in the fuel?


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8/8/2018 3:27 AM

The TPS setting doesnt/shouldnt cause a misfire. All it does is tell the ecu how much gas to inject.

Did you test your stator while hot? If its cold its very possible it reads fine and the output is good. Once hot it could be bad. Same for other ignition related parts. Im not sure where the coil is exactly on your bike, but if its close to the engine it can get hot and short out or cause the resistence to climb high enough to be too hard to send voltage to the plug.

Just a small reference story..
Kawasaki themselves had to work with my kawi dealership to solve this same issue on my kx450. They basically described it as chasing a “ghost”. Everything on the bike measured perfect until it got hot after 5 mins or so of running. My bike didnt idle until the rpms were held high. And to get it started you had to kick it as fast as you could to build a charge. The stators output got weaker as the bike warmed up and the only way to keep power to everything was to get the rpms up for a higher output. Which on a kawi is 37v. It caused a mean misfire as well.

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8/8/2018 4:03 AM

I had similar issues and changed out all the fuel filters and installed the twinair gas tank sock so I don’t have this issue in the future. Bike runs fine now

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8/8/2018 6:17 AM

I try a different gas tank, ECU, condenser and regulator. Do you know someone with the same bike you can swap out parts?

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8/8/2018 6:49 AM

exbmxmx wrote:

Probably the previous owner! lol

Maybe water in the fuel?


It probably is your fault. What kind of warranty did I get on this thing? lol

I don't know that it's water, but you saying that did make me realize that I had opened a new can of T4 and poured it in there when the issue started. I rode it 2 nights previous on T4 from another can and the bike ran fine. I'll try some pump gas today and see if that has any affect or if it's just a coincidence.

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8/8/2018 6:51 AM

CarlinoJoeVideo wrote:

I try a different gas tank, ECU, condenser and regulator. Do you know someone with the same bike you can swap out parts?

Unfortunately, I don't. If I don't get it sorted with what I have on the way, I'm just going to order a boat load of parts and have to return what I can that I don't need.

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8/8/2018 8:17 AM

exbmxmx wrote:

Probably the previous owner! lol

Maybe water in the fuel?


Braaaphole wrote:

It probably is your fault. What kind of warranty did I get on this thing? lol

I don't know that it's water, but you saying that did make me realize that I had opened a new can of T4 and poured it in there when the issue started. I rode it 2 nights previous on T4 from another can and the bike ran fine. I'll try some pump gas today and see if that has any affect or if it's just a coincidence.

Very Limited Warranty Included! Please read the fine print below for coverage details...


I was thinking the water would have come in from washing the bike but who knows? T4 has a very small capacity for water while ethanol based pump fuel has a much higher capacity. So adding some ethanol pump fuel would be a good idea or you can also go to the auto parts and get some gas tank drying additive, which is isopropanol. A very small droplet of water sitting on top of the fuel injector can cause all kinds of issues. I do have pure methanol, ethanol and isopropanol if you wanted to squirt some in the fuel line at the quick connect and then crank the engine over to make sure the fuel system is dry.

Let me know if I can help...

Greg

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8/8/2018 7:36 PM

exbmxmx wrote:

Very Limited Warranty Included! Please read the fine print below for coverage details...


I was thinking the water would have come in from washing the bike but who knows? T4 has a very small capacity for water while ethanol based pump fuel has a much higher capacity. So adding some ethanol pump fuel would be a good idea or you can also go to the auto parts and get some gas tank drying additive, which is isopropanol. A very small droplet of water sitting on top of the fuel injector can cause all kinds of issues. I do have pure methanol, ethanol and isopropanol if you wanted to squirt some in the fuel line at the quick connect and then crank the engine over to make sure the fuel system is dry.

Let me know if I can help...

Greg

Thanks. I'm still holding on to hope of it being the fuel filters. I keep reading where numerous people have had the same issue that was caused by the filters. Even the KTM mechanic I spoke with immediately started leading me down that road.

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8/9/2018 7:50 PM

Changed the spark plug cap and the in tank fuel filter, it runs great now. I highly doubt the spark plug cap had anything to do with it. Thanks for all the help

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8/16/2018 4:03 PM

So much for that, now it's doing the same shit again and seems to be worse. There goes racing this weekend, no way I can get it fixed in time. This bike is really making me start to hate it.

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8/16/2018 5:45 PM

Braaaphole wrote:

So much for that, now it's doing the same shit again and seems to be worse. There goes racing this weekend, no way I can get it fixed in time. This bike is really making me start to hate it.

Maybe a weak or dying pump and changing the filter created less of a draw/restriction on the pump causing it to work for a short time... I’ve also seen the o-rings on the injector deteriorate and plug the injector

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8/17/2018 7:50 AM

Braaaphole wrote:

So much for that, now it's doing the same shit again and seems to be worse. There goes racing this weekend, no way I can get it fixed in time. This bike is really making me start to hate it.

Paul_Pitzonka wrote:

Maybe a weak or dying pump and changing the filter created less of a draw/restriction on the pump causing it to work for a short time... I’ve also seen the o-rings on the injector deteriorate and plug the injector

I'm probably about to order a fuel pump, just too bad they are $300. I'd really like to check the fuel pressure before replacing the pump but I can't find a gauge locally. Guess there's always amazon.

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8/17/2018 8:53 AM

Not sure how your dealership works, but mine spent an entire week diagnosing my bike and charged me the 1 hour that kawasaki gives to diag a bike. That might be the best way to do it.

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8/18/2018 3:25 PM

Looks like it's finally fixed, damn spark plug. I decided to try changing last night not expecting any difference, bike fired right up and ran great. Went to the track today and never had an issue, bike ran perfect. I've never seen a spark plug cause such an issue, usually it either works or it doesn't. Oh well, easy fix in the end and I get to race tomorrow. Well, everyone else gets to race and I'll cruise around at the back of the pack.

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8/21/2018 8:25 AM

Braaaphole wrote:

Looks like it's finally fixed, damn spark plug. I decided to try changing last night not expecting any difference, bike fired right up and ran great. Went to the track today and never had an issue, bike ran perfect. I've never seen a spark plug cause such an issue, usually it either works or it doesn't. Oh well, easy fix in the end and I get to race tomorrow. Well, everyone else gets to race and I'll cruise around at the back of the pack.

Was it the cap itself causing the issue or just the spark plug? I have the 450 which uses the same cap and was wondering if the cap (or plug) is something to look out for if i get the same issue in the future. Did you closely inspect the spark plug? See anything out of spec? Gap? Thanks.

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8/21/2018 1:27 PM

The 450 and 350 do not use the same cap. Totally different styles as the 350 plug is down inside the center of the head.

250 and 350 are the same.

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8/21/2018 9:04 PM

MX915 wrote:

The 450 and 350 do not use the same cap. Totally different styles as the 350 plug is down inside the center of the head.

250 and 350 are the same.

Thanks!

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8/22/2018 12:52 PM

blaze 57 wrote:

Was it the cap itself causing the issue or just the spark plug? I have the 450 which uses the same cap and was wondering if the cap (or plug) is something to look out for if i get the same issue in the future. Did you closely inspect the spark plug? See anything out of spec? Gap? Thanks.

It was the spark plug. I didn't look at it too close. The electrode looked normal on it. There was a good bit of corrosion on the outside from getting wet when I wash the bike. I suspect the ceramic was likely cracked and allowing it to spark to the head.

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