FE390 Intermittent No Start

Ok, I have another infuriating problem. Last week, I was riding and everything was just fine. At one point, after one of many restarts, the bike started but then coughed and died. After that, it cranked fine, but wouldn’t fire. My first thought was that the dreaded hot-start, fuel-pump issue had returned. But, the fuel pump was spinning (verified via the quick *** of the starter button and the ear to the tank). I inspected all the fuses. All were ok and then it fired right up and ran fine. I had no problems the rest of the day.

Today the same thing happened. I rode 97 miles. About half way through, it did exactly what I described above. I tried to start it about 5 times, then I fiddled with the fuses and it started and ran fine. The total down time was maybe 5 minutes. I really think the fuses are a red herring. I can’t imagine how anything loose would only cause a problem on start up.

At about the 95 mile mark, it did it again. This time I immediately fiddled with the fuses, but it would not start. I then fiddling with plug cap and cold start knob. It still wouldn’t fire. Then it did an all was fine again.
I washed the bike and checked everything I can see (without tearing it apart). I started it, stopped it, and restarted it half a dozen times and it’s fine. I let it heat up until the fan came on, stopped it and restarted it and it’s fine.

Each time it has done this (3 times so far) I have verified that the fuel pump is spinning. I also wiggled the spark plug cap and tried pulling the cold-start knob. Nothing seems to have any effect, but then it all of a sudden cures itself and runs fine. Any ideas what I should look for?

Thanks.

look for a crack in the porcelain of the spark plug. apparently there was a dodgy batch of them.

regards

Taffy

Yes, I experienced that myself. I checked but didn't see anything. I seem to be getting a good spark from my plug (about 8 hours on that one). It's been very wet lately. I did notice that the main fuses were wet. Those clear plastic covers were filled with water. I cleaned them out, put in new fuses and filled the covers with dielectirc grease. I put the grease on other connectors as well. I'll see what happens this week. I'm not confident that anything will change. Thanks.

usually a missfire under load is spark getting away at HT level.

regards

Taffy

I'd never heard that tip before Taffy. Thanks for the advice!

usually a missfire under load is spark getting away at HT level.

sorry, what is "HT level"??

mine is stalling at low rpms/throttle openings

HT is High Tension voltage from the HT coil.

Regards

Sparks.

Thanks for the suggestion. But isn't the load while running the same as it is at startup? I could see a faulty coil causing weak or intermittant spark, but I don't see how it could only show symptons at start up. Am I looking at this wrong?

You said it has been wet, a mate of mne had a dodgy spark plug cap boot that let water in and made the same symptoms, it would die and the not start, then after 5 minutes of drying out it would start.

JohnnyQuest said:

Thanks for the suggestion. But isn't the load while running the same as it is at startup? I could see a faulty coil causing weak or intermittant spark, but I don't see how it could only show symptons at start up. Am I looking at this wrong?

Click to expand...

Hi JonnyQuest,
the 'load' on the ignition system is a function of many things, but importantly includes what is between the electrodes of the spark plugs (air, or a fuel/air mixture, or something else), and the pressure of whatever exists in the spark gap. Plain air will need a higher voltage for the spark to 'break-down' the spark gap and start the spark than an air/fuel mixture; a high pressure similarly increases the spark gap break-down voltage.

The maximum pressure in an engine at the time of the spark is usually experienced during starting (no throttling and late ignition timing to avoid the possibility of the engine going the wrong way). This makes the spark break-down voltage quite high. Then there's the possibility the spark may occur in a leaner than normal mixture during starting... which also increases the break-down voltage.

Stirring in the effect of a cold start amplifies the affects somewhat too, for many reasons (the physics is a bit long-winded, so I'll leave it out unless you really want to know...).

The bottom line is the break-down voltage during a cold start can be the highest it will ever be. Very much higher than in an idling engine when it's fully warmed up. The only way you can approach (or in special cases exceed) the break-down voltage during a cold start is when the engine is around peak torque speed and the throttle goes through a massive transient (wide-open, to off, to wide-open again very rapidly). A lot depends on ignition timing, spark plug design, inlet port length, valve timing and a few other wonderful things too, so it's difficult to say this will apply in your case.

Why do we care? Well, the spark plug insulator, the cable, the cap and all the high voltage side of the coil must be able to withstand a voltage higher than that needed at the plug electrodes. If it cannot, the spark will not appear at the electrodes where it's needed, but will simply shoot through, over or around the insulation to ground... and you get a misfire as a result. Under starting conditions the problem usually results in a simple failure to start!

However, having said all that, I suspect it's not your root problem. What you describe is reasonably indicative of a failing crank position sensor (CPS) in my opinion. The sensor could be fine, but something may be attenuating the signal such that at low speed (cranking), the ECU fails to recognise the engine is moving. Once the engine is running, the CPS signal will be much bigger (assuming a 'VRS' type of sensor), so there's no longer a problem. If you've a dodgy connector with some corrosion it may occasionally be enough to get the engine going, but occasionally not... depending on how wet the corrosion layer is. And your connectors sound like they could be a bit wet!

If I were you I'd start by looking at the CPS, its air-gap to the trigger wheel, its cable to the harness, and ultimately its connection with the ECU.

Cheers and regards... Paul

I also had similar problems on my 570. The problem only occured after long riding in wet/snowy conditions.
After new spark plug cap (and new spark plug) the problem was solved.

tinwelp said:

If I were you I'd start by looking at the CPS, its air-gap to the trigger wheel, its cable to the harness, and ultimately its connection with the ECU.

Click to expand...

FI light "should" show a fault if there was a short or open circuit (at a guess). The Crank Position Sensor (CPS) is just a simple coil of wire:
2 x short flashes = Crankshaft position sensor

The CPS is not adjustable according to the Workshop manual. See post here:
VAPOR LOCK: THE FINAL SOLUTION!

It’s absolutely, positively the fuel pump. Again! I was in denial when I said it wasn't the fuel pump this time. My dealer gave me the tank off his demo bike last August, but I never received a new pump. I think August was a bit before Husaberg officially recognized the problem and started replacing pumps so I just took my dealer’s tank complete with the pump.

I log all my rides. During the first ride with that tank back in August (85 miles) it “only” failed to start 1 time and then fired up after about 1 minute so I figured “close enough!” During my subsequent ride, it did the same thing, but again fired after 1 minute. I then rode it 4 times without incident and thought the problem was cured, but my log book shows that the ambient temp never got above 45 degrees F. That brings me to 2011. On my first 2011 ride when it’s been hot, the bike failed to start once, but did fire after about 5 minutes so I figured it was not the fuel pump. On the next ride it failed to start twice. I could hear the pump spin sometimes but not others, and the sound of the pump seemed “odd” now that I think about it.

Last night (90 F), it failed to start every time I shut it off and the pump either did not spin or spun with a distinct laboring sound. The laboring sound (like a pump in pain) was what I heard during my earlier rides.

The good news is that I have positively identified the problem. Now I need to get Husaberg to give me a new pump since I’ve been dealing with this since I bought this bike and have logged only 6 problem-free rides out of 27!! My wife said, “How can you stand that! You need to trash that POS and buy a new bike!” That’s the first time my wife ever told me to buy anything other than underwear!

JohnnyQuest said:

buy a new bike!” That’s the first time my wife ever told me to buy anything other than underwear!

Click to expand...

now that's funny, and if you don't think so...then you aint married!

My wife said the same thing except she added...you can't even sell the POS if it doesn't run!

I've got the same problem.. After cleaning the white gunk out of the tank (which was after 2 rides and the bike died) I thought my problems had disappeared. Bike ran great for exactly 27 hours then the fuel pump has done excactly what you have described above. It let me down during a hair scramble and boy I was some upset.. It progressively got worse and worse the next time out with the bike dieing every 10 min or so. I do have another pump on order $515 Canadian :cuss: .
I decided to tear into it last night and have a look at things and pulled the fuel filter, which was partially clogged. Gas would flow through it but it would take the pump some extra effort to work properly. So I am guessing the gunk in the fuel tank will continue to come off over time and slowly clog the filter up, putting extra labor on the pump and helping it to die that much sooner.. Just my guess..
And at the race I must mention out of the 6 or 7 newer bergs there 3 of us could not finish the race due to overheating fuel pumps...

Yeah, it seems that just one Berg misbehaving at a race or event is enough to make everyone there think that a Berg is not worth the trouble. Three dead ones must make quite a statement. It sure seems that this problem is common enough that Husaberg needs to fix it ASAP. No matter what it costs them, it will be benefit their reputation much more than any advertising ever could.

There is a poll thread over on KTMTalk in the Husaberg section regarding this issue. The thread is trying to get everyone who is having or has had fuel pump issues to log some basic bike information. Hopefully this will draw more attention to the extent of this problem.

Same problem here in hot Brazil, after some riding if I turned the engine off for about 3 or more minutes then it would take something between 10 to 15 minutes to restart.
Solved it by using 1% of 2 stroke oil mixed with fuel.
Now have a 2012 TE 300 but the 390 new owner still uses the mixed fuel and no problems so far.