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Engine Stalling


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Hello. On the way home from an 8 day, 2,700 mile ride up into Michigan and Wisconsin (and Road America superbike races), I was in a construction zone about 100 miles from home, doing about 45mph, just maintaining that speed (not coasting nor accelerating), when the engine quit running. I felt a stumble or two, and it quit. I pulled in the clutch, coasted a few seconds, and thumbed the starter. The engine started just fine, but would not idle. It pulled just fine when given throttle, but would not idle.


A little ways down the road, it did it again under similar circumstances.


The engine had been acting a bit strange prior to that, with it idling very smoothly at times, and very roughly (feeling like it was missing one cylinder). There didn't seem to be any rhyme or reason or pattern to the intermittent rough/smooth idle.


The bike is an 09 RT, with 47K miles. The fuel pump controller was replaced at 22K miles.


Any ideas as to what to look for? It's going to my private mechanic next Tuesday for brake flush, throttle body sync, computer check, and a couple other minor maintenance items. I'd like to give him some things to look for, so whatever ideas you might have will be appreciated.

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Early in my 08's history, a similar set of symptoms led the dealer to replace the cam position sensor. Evidently the main engine control unit didn't know when to spark (no retard). The engine started and ran OK only over 2000 RPM - but would not stay running below that.


Based on my reading of these forums that's a rare failure mode and one that seems similar to a failed FPC. FWIW.

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Stepper(s)? There have been a few reported cases where these caused failures in highway running at throttle roll offs...

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Afternoon siman00


That is going to be difficult to diagnose if it didn't store a failure code in the computer.



A strange acting stick coil could also be the cause but that usually doesn’t run very good at higher throttle settings or higher engine loads ether. (this one would be down my list a ways)


Something like water in the fuel could be the issue so if it goes way & never returns suspect that was the possible cause.


A TPS issue maybe (that should leave a failure code)


An FPC issue but that should also leave a failure code.


Otherwise one of the engine sensors but most of those will leave tracks in the form of a failure code.


Even a side stand switch could be the issue if you hit it with your foot or it sticks a bit.


Other than the stall while cruising at a constant 45 I would guess one of your idle stepper motors was lost. If so that is a very difficult thing to diagnosis as it leaves no tracks in the system. (If you were at closed throttle during the stall this would be my #1 guess) . Stalling at 45 mph with an open throttle not so much. Stepper issues usually show up with clutch pulled in at idle or coating to stop with a closed throttle. On manual transmission vehicles stepper motor issues seldom cause a stall as long as you still have throttle control & the wheel can keep the engine spinning.


The " but would not idle. It pulled just fine when given throttle, but would not idle" also points to possible stepper motor issues or a vapor locking issue. Fuel injected engines very seldom vapor lock but it can happen with the wrong vapor pressure gasoline.



See if your tec can pull up any failure codes. If not suspect fuel issues. If your problem doesn't return then especially suspect fuel issues.


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Hi Siman00,

Having suffered from a stepper motor failure on my '06 R12RT, I'm inclined to discount that, as DR says.

Mine NEVER cut out when running under throttle, only when throttled off to slow down or stop.

I had similar symptoms to yours on a ride back home from the south west of England.

Bike started without a problem, but failed to tick over, or run below 2,000 rpm or so - not fun when stuck with three lanes

of motorway / freeway traffic for 15 or 20 miles in a rush hour!

Had the bike in to the dealer, but no codes stored, and their diagnosis was bad fuel / water in the fuel.

I added some fuel drier, and have not had a recurrence some 30 months and 20,000 miles later.

I'd try that first if it were mine. Hope it's soon resolved in any case.

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Thanks for the suggestions and comments. I think I'll try some fuel conditioner first, and then see what the mechanics say next week. I'll probably bring a copy of these comments with me so that they will have your thoughts.


What fuel conditioner do you recommend--something like Sea Foam?

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Evening siman00


If it is a fuel problem (a good possibility) we really don't know if it was a moisture issue, or incorrect vapor pressure, or something else.


If a moisture problem then something like Dry Gas is probably best but you really don't want to add any more alcohol than you already have in there. So with Dry Gas out then Sea Foam is probably not a bad choice. (don't over do it as too much can settle out when you let the bike sit for a while)


The best way to deal with bad gasoline is to drain it out or just ride it out. Once most is gone then put in GOOD new gasoline.


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