390FE Spark Question

wetsiderider · Oct 30, 2012

My 2010 390 won't start after some headwork. I get one spark to the plug when the starter button is pressed, then no further sparks. Engine turns over fine. Dealer said, on the phone, that it's a "loose connection". I've checked everything I can think of but no success.

Main harness connection (starter relay) looks good, coil connection looks good. The owner's manual refers to a circuit ignition pulse generator, but I don't know what that is, or where it is to check the connection. Is that camshaft position sensor by another name?

Davo · Oct 30, 2012

There is no Camshaft Position Sensor on these bikes.
There is a Crankshaft Position Sensor. The 2 x wires for that come out of the Left Hand Side of the Bike (Gear stick side). If you look directly north of the Chain Sprocket you will see the 2 wires coming out of the engine.

They go straight to the EFI ECU as per this diagram:

There should be 1 wire from the Coil that goes back to the ECU (Pin 18). There is no external Ignition Module for the Coil. The Ignition module must be built into the EFI ECU.

When you hit the starter button for 1 second can you hear the Fuel Pump noise start?
Does the EFI Light flash any codes while you are trying to start it? It should flash a sequence of flashes short and long to indicate a wire is loose or shorted etc...

It could just be something simple like the High Tension Lead on the Coil or a Crack in the Spark Plug Cap or the Spark Plug. Have you checked those things?

Davo

wetsiderider · Oct 30, 2012

No codes get dropped during start cycles. I can get codes when I disconnect the fuel pump power, or the intake temperature sensor, but they disappear when the item is reconnected.

The coil will fire the plug when fed directly from the battery with a test lead. Interestingly, the fuel injector only fires on initial starter depression also. So, one spark, one fuel pulse, then nothing.

According to this post,

viewtopic.php?f=6&t=16251&p=134207&hilit=390+spark#p134207

I tried disconnecting the TP Sensor, but I have the same symptom with the connector disconnected, one spark, one fuel pulse.

I disconnected the crankshaft position sensor connector, then I got no spark. I disconnected the voltage regulator connector, and again, no spark.

Visually inspected the rollover sensor, and even with it unplugged, the same symptom comes up, one spark, one fuel pulse.

I have a brand new Ballistic EVO2 battery in the bike, and it shows 13.2 volts, drops to 11.8 when cranking.

I'm a little skeptical that any electrical component would fail without a code coming up, but nothing is impossible. I suppose I should drag it up to the dealer next and have them do a diagnostic on it, but since no codes are showing, I'm not sure where they would start. Their advice on the phone was to "check for a loose connection". Not bad advice, but so far, no love.

wetsiderider · Oct 30, 2012

Oh, and yes, I get fuel pump noise after initial start.

Thanks much for the info, too.

Davo · Oct 31, 2012

Yeah, I agree, you would think it would be a flash code if there was a loose wire or faulty sensor.
There would be no code for a faulty secondary winding in the Ignition Coil, or the Coil Lead, or Spark Plug Boot or Spark Plug. But like you said it sparks with a battery.

I wonder if it could be the rollover sensor?
If you bridge a wire between pins 5 and 6 in the XC1 connector the Berg will stay powered up. This may give more time to see Flash Codes.

Shorting pin 5 and 6 in the XC1 Connector also bypasses the Regulator so if there is a fault in the regulator part of the circuit, your bike will start with pin 5 and 6 shorted.

The XC1 connector is in the picture below, just to the right of the Fuse Box. It is the white loose connector not plugged into anything. There is a cover on it to keep the dust out. It has 6 wires going to it. It is what the dealers plug their diagnostic tool into to check things and re-flash the EFI computer.

The chunky thing below the Fuse Box in the picture is the Starter Relay.

Davo.

Bergini · Oct 31, 2012

There you go again Mr. Service Manual, textbook illustrations and color photo's :lol: Very nice

wetsiderider · Oct 31, 2012

I've used the bridging between 5 and 6 on XC1 to read the codes. No code comes up for rollover, though I can create a code by disconnecting it.

I'll try to start with a bypass of the regulator tomorrow.

I'm starting to think this is a connector problem. On the wiring diagram there are little bullseye symbols with designations like -X5. Are those connectors and not splices? I'm suspicious of connections X9 and X10 that look to be shared connections for TPS and Rollover to the EFI Unit. I'll start searching for those to check next.

And thanks again for a great detailed response.

wetsiderider · Nov 1, 2012

Bypass of the regulator (bridging pin 5 and 6 on XC1) gives no spark, as opposed to a single spark on initial depression of starter button.

Davo · Nov 7, 2012

Hey Wetsiderider, did you find out what the problem was?
It would be great to know what it was for the next time someone has that problem.
Cheers,
Davo.

wetsiderider · Nov 8, 2012

Now I have to confess my poor electrical skills. There is what my dealer calls a diagnostic connector associated with the kill switch. I had inadvertantly plugged a loose connector from my turn signal wiring into that diagnostic connector. Once removed, problem disappeared.

It was the single spark that got me, I think. NO spark might have led me to examine the kill switch more carefully, but I still might have been blind to it.

jjm525 · Dec 24, 2012

I am suffering thru a single spark scenario myself now. Bike was running badly, had to turn the idle up all the way to keep it running, started intermittantly. I pulled the injector and had it cleaned, now the bike won't even start. Tried adding fuel but dead.

I pulled the plug cap off the wire and find it gives one good spark on turn over and then nothing.

I swapped out the stator pulse pick up tonight with a new one as the dealer had a few KTMs give similar symptoms. No dice. I unplugged the TPS and same thing.

Anyone have a good place to look next?

Thanks.

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390FE Spark Question

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