Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 999 / 749 > 749s motor cuts out when fans cut in WHY?

[banana749]

Can anyone help/had the same problem? I ran my 2003 749 up to temp on the drive, I have never heard the fans cut in, (it normally runs at about 72 degrees) so I thought I would just see when they cut in. At 103 degrees the fans duly started spinning which immediately cut the engine, running at about 2000rpm at the time. I waited til it had cooled down to about 60 then tried starting, dead, starter won't turn! Plenty of lights on the dash all seems fine but won't spin the starter.

[yeti]

Sounds like your charging system might be on the way out. Bike was using battery power to run the ignition, fuel injection, dash etc, but when the fans cut in it was just too much and the battery voltage dropped enough to kill it.

If you have one, it might be worth seeing what a multimeter says your battery voltage is now! I'd hazard a guess it's less than 12v

[testastretta]

Originally Posted by banana749

Can anyone help/had the same problem? I ran my 2003 749 up to temp on the drive, I have never heard the fans cut in, (it normally runs at about 72 degrees) so I thought I would just see when they cut in. At 103 degrees the fans duly started spinning which immediately cut the engine, running at about 2000rpm at the time. I waited til it had cooled down to about 60 then tried starting, dead, starter won't turn! Plenty of lights on the dash all seems fine but won't spin the starter.

Hi - been reading your problem, forgive me 'thinking things thru out loud' but that sometimes helps :

Bike started fine, ran til fans cut in
Bike then cuts out,
Re-start attempt shows lights to instrumentation but starter does not spin
You didn't mention if main lights still work, and I can't recall if they only come on after engine fires up
May well be charging is not as it should be, but even if battery is down on power, I cant see that such a sudden cut off would leave it so depleted on power (having had enough in it to fire starter up in first place) to not have anything left at all to even turn the starter motor, but other chap might be right. Check your fuses too anyway, just in case.

[testastretta]

Originally Posted by testastretta

Hi - been reading your problem, forgive me 'thinking things thru out loud' but that sometimes helps :

Bike started fine, ran til fans cut in
Bike then cuts out,
Re-start attempt shows lights to instrumentation but starter does not spin
You didn't mention if main lights still work, and I can't recall if they only come on after engine fires up
May well be charging is not as it should be, but even if battery is down on power, I cant see that such a sudden cut off would leave it so depleted on power (having had enough in it to fire starter up in first place) to not have anything left at all to even turn the starter motor, but other chap might be right. Check your fuses too anyway, just in case.

How are you getting on - have you cured problem ? Ronnie

[testastretta]

Originally Posted by banana749

Can anyone help/had the same problem? I ran my 2003 749 up to temp on the drive, I have never heard the fans cut in, (it normally runs at about 72 degrees) so I thought I would just see when they cut in. At 103 degrees the fans duly started spinning which immediately cut the engine, running at about 2000rpm at the time. I waited til it had cooled down to about 60 then tried starting, dead, starter won't turn! Plenty of lights on the dash all seems fine but won't spin the starter.

How are you getting on - did you cure problem ? - Ronnie

[KeefyB]

Is the orange EOBD light of death on?
Could be one of the sensors thinks the bike is overheating and imobilised it.