ST4s non start issue
 

Hi

Posting this here as I don't seem to be able to fix myself.

My ST4s has decided to stop starting all of a sudden.

- Battery cranks the engine OK
- Sparks go to the plugs OK
- Fuel pump primes OK
- I have an alarm on it but have bypassed it using a replacement loom and problem remains

- I have tried resetting the immobiliser by turning on with Red Key - then turning on with each of the spare keys.

- I have not tried the side stand switch but have a side stand bypass anyway and can start on the side stand.

Problem happened all of a sudden, no sign of weakening at start or else.
Rode the bike to work in the morning with no problem whatsoever.
It decided not to start on the way back and got stranded.

It looks like the problem is that no fuel is spit by the injectors.
I have removed the airbox and looking into the throttle bodies and it is stone dry in there.

Any idea what could be the problem?
Do you know if the immobiliser cuts the injection?
Would I need to change the little black box on the side?
Do I need to change ECU as well?

Please let me know if you have any idea?

Cheers
philippe

Not suffered it myself but i understand the internal tank fuel pipes can split when they are old.

This would mean that the pump is doing its job but the pressure is gone.

It might be worth trying to see if you can remove the fuel supply pipe from under the tank and determine whether the fuel is either not coming out under pressure or whether the injectors are not delivering what is supplied to them.

I think that I have identified the issue.

It was the immobiliser. I have redone the Red key sequence as I did not realise that there was some very specific sequence/timing to respect.

Looks like the bike is starting now.

Still puzzled how something would have reset itself and the bike stopped starting for some reason.

p

Interesting that you managed to reset it by reprogramming the keys.
It may be you ran down both the main battery and the internal backup battery in the immobiliser? I've never taken one of those style immobiliser boxes apart to see what's inside, so it would be interesting to see if there is a battery backup.

Problem is back.
Managed to reset twice but this morning, nothing doing.
Does anybody know if there is a way to bypass?
Surely it is just verifying the key is ok and allowing the juice to flow.
I would doubt that it has the sophistication of a CAN comm with ECU?

Phillipe it might just be the Ariel or the Ariel lead that picks up the transponder in the key, have you another one you can try or any one close by got one you could borrow

I have a 2002 ST4S and I had big problem with it's temper that the engine can start sometimes but sometimes not. I have to walk away having a coffee and most of the time when I come back , the engine starts untill even this could not work after the battery is empty out , recharged, and empty out.
I tool the bike to Ducati dealer and test it on computer, nothing abnormal was found.
They changed the relay and the sensors for me. Now, it's temper is a lot better. It does not start sometimes but after a few teimes of trun the key on and off, it starts. Seems like the problem is still there but just not as bad as before.

Have a chat with Anthony at Avanti Race Parts as he has some insight into the ST4S's failings and ways of curing them.

if worse when engine warm, may be crank sensor starting to break down,
hence ECU is not seeing engine turning over, and injecting fuel etc
problem is verifying if that is the culprit.