Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > Supersports: SS / SuperSport / Supersport 950 > Bike Lurching/Surging/Coughing Problem - Help!!

[phillc]

So my 2002 900ss is playing up big time.

It has developed what can only be described as a surge or cough when under power. No other way I can describe it really. Usually, whenever the revs get close to 5,000rpm and above, there is a sudden, short loss of power, then it picks up again. Sometimes this will happen once in a while, every mile or two perhaps. Other times it happens almost constantly.

I've tried to figure out if it happens when hot or cold, doesn't seem to matter. Tried to figure out if it's with full or empty-ish fuel tank, doesn't seem to matter. Tried to figure out if it happens at different rev ranges and usually it is between 5k and 6k rpm, but this morning it was particularly bad and happened all the way from 3,000rpm upwards.

So far I have done the following:

- drained the fuel tank totally. And there was a significant amount of water in the bottom - about 1 inch in the bottom of a 1 litre plastic drink container.

- change the fuel filter. Did both of these at Cadwell on Tuesday. I had 15 trouble free miles on the way home, before the problem started again.

- Changed old spark plugs for new. Fortunatelly my 900ss and my DD bike use the same plugs and I had a spare set.

- Put the standard pipes and airbox back on. The problem was still there, just that the "buck" of the bike didn't seem so bad with the standard pipes on.

All of the above has been to no avail. Problem still happens.

Someone suggested that it could be my potentiometer, but the SS ECU doesn't have one.

I'm supposed to be riding to Normandy on Friday evening for the bank holiday weekend. However, at this stage I'm not sure the bike is up for it. Looks like my weekend could be stuffed.

Any ideas? I guess it's too late to get it into a workshop now, but is there anything else I might try?

Help!

[KeefyB]

Fuel tank breather partially blocked??

[phillc]

Originally Posted by KeefyB

Fuel tank breather partially blocked??

Now there's an idea........

I had this blocked once before and it caused this:

http://www.kapital-sales.co.uk/desmo...Tank%20001.jpg
http://www.kapital-sales.co.uk/desmo...Tank%20009.jpg

I'll check the breather pipe because I did notice this afternoon a "hissing" coming from around the fuel cap. I did think perhaps it was something I'd done in not putting it back together correctly after changing the filter.

Any thoughts on the best way to clean/clear the breather?

[KeefyB]

Cant remember how the breather is routed on the I.E bikes,but when my wife had a carbed SS,I cleaned out a blockage by pushing a lengh of 4mm electrical cable down it.

Oh yeah,I remember those pics.Incredible!

[phillc]

Originally Posted by KeefyB

Cant remember how the breather is routed on the I.E bikes,but when my wife had a carbed SS,I cleaned out a blockage by pushing a lengh of 4mm electrical cable down it.

OK, maybe I'll try a twisted piece of lock wire or similar. Thanks for that.

I should also mention that I spent some time this evening checking that the fuel line wasn't kinked anywhere, thus reducing the flow of fuel.

Any further ideas?

Had similar issues before on a 900SS was an HT cable breaking down under load, finally traced it by spraying water onto leads via a greenfly killer in the garage in the dark and seeing the break down, I know 'how those long winter evenings must fly by', but bl**dy found it eventually !!!

[Jools]

Originally Posted by KeefyB

Cant remember how the breather is routed on the I.E bikes,but when my wife had a carbed SS,I cleaned out a blockage by pushing a lengh of 4mm electrical cable down it.

Oh yeah,I remember those pics.Incredible!

I dunno about SSie's either but on the ST the breather is a little round can about the size of a 10p piece and about half as deep with an air inlet sticking out the side. It's a one way valve and it sits on the bottom of the fuel pump assembly.

[skidlids]

how about getting it plugged into a diagnostic machine in case its a sensor of some kind.
The guys from MotoRapido were kind enough to plug theirs in to Dallas's bike on Monday at the trackday and it revealed a rpm sensor fault.

[Jools]

Originally Posted by skidlids

how about getting it plugged into a diagnostic machine in case its a sensor of some kind.
The guys from MotoRapido were kind enough to plug theirs in to Dallas's bike on Monday at the trackday and it revealed a rpm sensor fault.

Bugggerit...if I'd known they had one of those at the trackday

[phillc]

Originally Posted by Jools

Bugggerit...if I'd known they had one of those at the trackday

Yeah, I've just had a little swear too.

My main problem is that I don't have the time to get it to anyone with a diagnostic machine before I'm due to catch the Eurotunnel on Friday evening. So, I'm prepared to try everything I can myself at this stage!

Maybe a diagnostic machine is the only way to go......