2014 SXF 350 no fuel pump no spark no FI light

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6/9/2019 11:33 AM

Hello guys,

yesterday i was practicing a few laps and decided to get back to the car to get some water and rest.
I wanted to make a few final laps before going home but the bike was unable to start.

the starter is turning but there is no power to the ecu, fuel pump etc.
went back home and did some research. when i jump-wire the power relais the ecu starts up as well as the fuel pump and i can start the bike like normal. i check all the wires for rubbing/breaks and did continuity tests. As the bike is in like new shape and has never been tinkered with all the connections are ok. i checked the voltage over the coil of the power relais. The relais never gets energized it seems because there is no ground connection established. I removed the power relais and checked it seperately with a bench power supply and ohm meter, everything perfect coil reads 80ohms as it should. on other topics here i read that these people got exactly the same problem but never posted their solution:
https://www.vitalmx.com/forums/Race-Shop,42/2014-KTM-250-sxf-no-spark-no-fuel-pump-power,1293341
https://thumpertalk.com/forums/topic/1232320-2015-ktm-sx-f250-turns-over-no-spark-and-the-fi-light-not-coming/


It seems that the power relay gets its ground connection from the regulator when the AC phases (2 yellow wires from stator) provide voltage as soon as the rotor spins and i think here is my problem. Can it be that my regulator got fried because it was very hot outside yesterday? i made a diode check for the rectifier part which seems okay. as the regulator is very pricy i dont want to purchase it when im not 100% certain.
Photo


here is the diagram portion of the power relay (K30). The white-black wire must be grounded and leads to the regulator and also the ECU. Do you guys kno how this grounding takes place?


Best regards and many thanks in advance

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6/9/2019 11:52 AM
Edited Date/Time: 6/9/2019 11:53 AM

Not sure, but are the mounts the actual ground? If so look for rust or bad connections.
Battery voltage good under load?
Have you checked the starter relay?

Paw Paw

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6/9/2019 11:59 AM

I had the same thing on a 14 250 sxf and it was the regulator

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6/9/2019 12:05 PM

i recharged the battery it goes down to 10.6V under load when starter is turning which seems pretty good to me.

i checked the ground brown wire is coming from ktm (GND) going in to the green one on the regulator. but the green one on the reg is not connected with the chassis of reg.
when the reg is really broken i want to try a chinese replacement for 20$. In the meantime can i ride on bumping the power relay at every startup with a wire? it seems that the starting relay only has to generate a pulse and is not"on" all the time because when i dip it with a wire and remove it after the bike fired up everything idles normally.

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6/9/2019 12:07 PM

809 wrote:

I had the same thing on a 14 250 sxf and it was the regulator

thanks 809 for your reply, i was thinking of you because your thread was the best one suiting my problem

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6/9/2019 1:32 PM

lc4_fan wrote:

i recharged the battery it goes down to 10.6V under load when starter is turning which seems pretty good to me.

i checked the ...more

Yes, I could do the same thing on the one I had. Sounds like it is the regulator for sure

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6/9/2019 1:51 PM

lc4_fan wrote:

i recharged the battery it goes down to 10.6V under load when starter is turning which seems pretty good to me.

i checked the ...more

809 wrote:

Yes, I could do the same thing on the one I had. Sounds like it is the regulator for sure

did you ride the bike with the shorting trick for a few hours or did you change out the regulator immediately?

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6/9/2019 2:23 PM

Changed it immediately. Didn't want to take a chance of it dying on a jump or something

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6/9/2019 2:30 PM

i would be very interested which circuit is inside of the reg switching the whiteblack/white wire on regulator to ground to energize the power relay coil. normally the regulator would only need 4 wires, 2 yellow ones for AC and + and -. A schematic would be really helpful.

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6/9/2019 5:44 PM

10.6 volts is too low. Get a LI battery.

Paw Paw

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6/9/2019 8:18 PM

lc4_fan wrote:

i would be very interested which circuit is inside of the reg switching the whiteblack/white wire on regulator to ground to ...more

I know, I should have taken the old one apart, but it ended up in the dumpster

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6/17/2019 6:44 AM

Hey guys,

for anyone else who has this problem i solved it now temporarely by wiring a small piece of wire in parallel to the white wire on the regulator. I just have to touch a piece of frame and start the bike afterwards. then the ECU is somehow providing ground internally for the power relay, keeping it actuated.

i found this out when i just quickly tapped the wire to ground and listenend when the relay clicked again and shut off -> many seconds after my "manual" attempt. I rode for 10hrs now with this "trick" without problems and purchased a 20usd chinese replica (which i think the original ones are cheap chinese shunt r/r too)

best regards

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9/5/2019 6:39 AM

lc4_fan wrote:

Hey guys,

for anyone else who has this problem i solved it now temporarely by wiring a small piece of wire in parallel to the ...more

Did you replace the voltage rectifier? Did it solve your issue? I purchased a cheap rectifier to address the same issue and it did not solve my issue. Wondering if the rectifier I received is also bad or if I have another issue.

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9/5/2019 8:58 AM

Hi, i have the new regulator unit at hands but i never changed it out. i have a small wire which i just tap to ground/frame and the fuel pump starts moving and than i just press the starter and the ECU grounds the fuel relay itself.

i think this is a good anti theft measure but it would be bad if the chinese regulator wouldnt word out of the box, now you made me curious i will plug it in one the weekend to see if pressing start button is enough to fire up

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9/5/2019 9:06 AM

maybe the cheap regulators havent implemented this grounding feature/switch when receiving AC and are just the basic 4 wire shunt R/R with 5 wires, one doing nothing... i hope not

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9/5/2019 1:06 PM

lc4_fan wrote:

maybe the cheap regulators havent implemented this grounding feature/switch when receiving AC and are just the basic 4 wire ...more

Keep me posted on what you find. I'm going to trace the white/black wire everywhere to make sure I don't have any issues. I can jump pin 87-31 and my bike start right up. I'll try the grounding the black/white wire as well. Maybe I can put that on a momentary switch and avoid future issues.

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9/5/2019 6:38 PM
Edited Date/Time: 9/5/2019 6:41 PM

i made a tap to the regulator wire which connects to the wh-bl on the KTM harness so i can make sure that there is no open wire in the harness from the bike itself. the wh/bl changes color at the regulator to plain white.there i have my ground switch. its so convenient to slightly press the switch and then press the starter button that i almost forgot about this issue

i think if the wh/bl wire would have an issue it would be most likely to touch the frame and you would hear the fuel pump turn on erratically

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9/5/2019 6:50 PM

Possibly not relevant...
I had the same problem on my 14 450 sxf.
The yellow with the shrink tubing broke...
Photo

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9/5/2019 7:10 PM

lc4_fan wrote:

i made a tap to the regulator wire which connects to the wh-bl on the KTM harness so i can make sure that there is no open ...more

To clarify, you ground the white wire out of the regulator using a momentary switch or a toggle switch? If a toggle switch, when do you turn it back off? Also, when you shut the bike off, can you reactivate your grounding switch and prime the pump right away again or does it take a minute for the relay to switch back?

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9/5/2019 7:24 PM

yzrider53 wrote:

Possibly not relevant...
I had the same problem on my 14 450 sxf.
The yellow with the shrink tubing broke...
Photo

Mine looks okay, both on the rectifier and the stator end

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9/5/2019 7:33 PM
Edited Date/Time: 9/5/2019 7:36 PM

lc4_fan wrote:

i made a tap to the regulator wire which connects to the wh-bl on the KTM harness so i can make sure that there is no open ...more

EDS_5_OH wrote:

To clarify, you ground the white wire out of the regulator using a momentary switch or a toggle switch? If a toggle switch, ...more

Exactly, i ground the white wire of the regulator with a momentary switch, a quick tap is just enough, than the ECU does something and grounds the wire of the power relay(pump etc.) by herself holding this state for approximately 20 seconds, you can hear the power relay click again after 20 seconds like when you press the starter button only shortly that only the fi light comes on and the pump primes and if you start the bike than it keeps grounding the relay. also if you turn the bike off or it cuts out in case of a crash you can start it maybe 20 seconds afterwards again without pressing the momentary switch.

best regards

edit: its not even a switch, i added a wire to the harness going to the handlebar with an open end and i just touch the clamp of the clutch lever with it, the connection to the frame clamp- clamp of handlebar - trippleclamp is enough to ground the power relay, the ECU senses this somehow and holds the ground like described above

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9/6/2019 6:36 AM

lc4_fan wrote:

i made a tap to the regulator wire which connects to the wh-bl on the KTM harness so i can make sure that there is no open ...more

EDS_5_OH wrote:

To clarify, you ground the white wire out of the regulator using a momentary switch or a toggle switch? If a toggle switch, ...more

lc4_fan wrote:

Exactly, i ground the white wire of the regulator with a momentary switch, a quick tap is just enough, than the ECU does ...more

Thanks for the information. I'll give it a try tonight. I did ground the white/black wire off the back of the fuel pump relay which did work and allowed the bike to start but when I shut the bike off, it would take 2 minutes or so before the relay would open back up the contact correctly.

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9/11/2019 7:54 AM

did you fix the issue?

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9/11/2019 9:16 AM

I added a momentary switch to the white wire coming out of the rectifier like you did that grounds to the triple clamp bolt. Works great.

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9/11/2019 11:09 AM

Sure sounds like a faulty starter relay. Almost everything goes through it.

Paw Paw

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9/11/2019 12:46 PM

Paw Paw 271 wrote:

Sure sounds like a faulty starter relay. Almost everything goes through it.

Paw Paw

I didn't see that relationship in the schematic but would be easy enough to try. The starter relay appears to be identical to the fuel pump relay and I have a spare.

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9/11/2019 11:50 PM

Paw Paw 271 wrote:

Sure sounds like a faulty starter relay. Almost everything goes through it.

Paw Paw

i dont think so, i tested the relais and with manual grounding they work just fine since 30h of running the bike

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9/12/2019 6:04 AM

I do wonder if the starter button could be to blame?

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9/12/2019 7:06 AM

no, you really have to study the schematics to see that only the regulator provides the ground for the main relaydriving the pump. the startbutton has 2 pins and only closes the magnetizing path of the starter relay.

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9/12/2019 12:05 PM

Paw Paw 271 wrote:

Sure sounds like a faulty starter relay. Almost everything goes through it.

Paw Paw

EDS_5_OH wrote:

I didn't see that relationship in the schematic but would be easy enough to try. The starter relay appears to be identical to ...more

No they are different. These are known to failure. It triggers the fuel pump when energized.

Paw Paw

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