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You know, ignoring the "old gas" issue, just reading your most recent comments I would question whether you might have a vacuum leak. The "starved proper fueling and it pops like crazy." sure sounds like the mixture is way lean, much more often a vacuum leak than a plugged fuel line.

If you've never chased down one, use some WD-40 with the extension tube to pinpoint spray potential leak areas while the bike is running. If there's a leak the rpms should increase. Also, use a bright flashlight when inspecting hoses for cracks. Speaking from experience, it's really satisying to find your "problem" is just a cracked hose. And if the emissions canister has been removed, make sure there's no open little connector tubes that should have caps. You may get lucky and solve all your problems with a little plastic cap from the auto parts store.

Just a thought.
 

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Discussion Starter #23
Well Mr. Jeff, you were right to look for a vacuum defect. There was one, vert cyl, the little rubber cap from canister removal done by p.o. It was split and I simply sliced off the bottom portion of split and thought that Jeff fella in Portland is damn clever. Alas, it is still hard to start but seems to idle easier.
As you all help me diagnosing this, with anything around half throttle, power is not really there. Rolling along 1-2nd gear, it’s not so much a surge but the pop is there and the presences of intake fart sounds certainly seem symptomatic. Thank you all for the help!
 

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Hallo RK :smile2:

I have had problems ala you describe.

Please see this thread:

https://www.ducati.ms/forums/77-sport-classic/722109-white-i-wait.html

and

https://www.ducati.ms/forums/77-sport-classic/716997-fuel-circuit-injectors-cloged-not.html



After beeing strandet for the second time I did a very thorough search for the reason the bike just died on me some times.

After searching the fuel system I did found out that the CPC Quick Release Metal Fuel Connector in the out port of the fuel flange was bad. Whether it was bad assembled or it did not have Viton O-rings I do not know. Either way the connector will restrict the fuel flow in some cases. The flow restriction is caused by swelling of the internal O-rings or if the O-ring not are seatet proberly. The inadequate or restricted fuel flow can cause engine stalling at throttle opening.

I did contact Motowheels but it seemed to be a loooong proces doing so, so I purchaced a new CPC Viton Connector at AFT Systems in Germany.

Now I have been riding my Paul Smart trouble free since I mounted the new connector (1600km / 1000miles).


I am not the only one who have had troubles with the CPC Connectors. This thread
https://www.ducati.ms/forums/77-sport-classic/616337-fun-new-fueling-issue-2.html did confirm I was on the right track.

All the best

Ciaooooooo


Moller
 

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Discussion Starter #25
Thanks Moller. They look proper but i will certainly heed your advice and keep an eye on those connectors.
Meanwhile I did remove injectors and there was just a bit of varnish around the edges. On the front cylinder, there was a fair amount of varnish where the injector fits and with carb cleaner and q-tips, I cleaned best i could, pretty spotless. Is it normal to see a a fair amount of varnishing in the intakes and the backside of the throttle butterflies? Will a product like the Lucas eventually cleanthat up? I have to say, still hard to start but I think getting a little better.
 

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Discussion Starter #26 (Edited)
Quick update is I decided to clean those intakes best I could w spray and removing the intake rubber boots and getting the injectors out of the way for the process. There certainly was a bunch of varnish yuck and question on the little ports, one ahead of the butterfly and 2 below. The 2 behind the butterfly appear to be emissions related, yes? The one in front of butterfly is idle? I didn't touch them but they were dirty, no doubt. Bike idles happier but now I'm hesitant to ride it with the popping still present. I don't want to do any damage. Still stumped by this...
Thanks for the additional thoughts and direction.
 

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Popping on deceleration is frequently a sign that you've got an air leak in the exhaust system. Maybe check the header pipes to verify they are secure to the heads, and look for any gaps at the joints between components?

Sounds like your getting it sorted out, let us know.
 

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Discussion Starter #28
Jeff how does this sound? I removed the fuel regulator and the big gasket at the base was shredded. I don’t know if that would create bad effect?
 

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Sounds like it’s fuel starvation so yes, fix that. Also, make sure fuel lines are not kinking or collapsing when tank is in place. Use actual reinforced rubber line, not the clear plastic stuff.
 

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Jeff how does this sound? I removed the fuel regulator and the big gasket at the base was shredded. I don’t know if that would create bad effect?
Well, any shredded gasket can't be good. By regulator, I'm assuming you mean the fuel pump mounting plate and it's large O-ring? Definitely fix that.

Exhaust leaks can allow your system to draw in outside air. Lean conditions encourage backfire, which is the Popping you're referring to. As delivered stock, my GT was very lean and would surge at steady throttle and buck & pop some on deceleration. That was on a new bike. I was able to cure the fueling woes pretty well with a fatduc unit, then went to a DP ECU later. Yours has been messed with by multiple people, all I can say is be methodical and eliminate the possible sources, which it seems that you are doing.

duc96cr has a good suggestion as well, you could well have an unfortunate combination of non-optimal mapping with contributing mechanical factors. Keep plugging away at it!
 

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Discussion Starter #31
As you all assist with your detective diagnostic skills, how’s this? It was cool yesterday, 50’s, and I hopped up, rolled away gently on our narrow and quiet backroads. The bike could not have been better. Proper power, no or minimal decel backfire, idled well. I feel the only variable besides more Lucas cleaner infused fuel flowing through the system was the weather. Let’s say it was a 20 minute ride.
After parking for say 15 minutes, the symptoms were back to being consistent w the above discussion. So the bike was super happy in motion at sunny mid 50’s morning...well who wouldn’t be? Does that condition prompt any further thought? Thanks for your input.
 

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I don’t understand why hoses would be capped off that used to go to a canister. Removal of the canister did not change their function, either to breathe out or breathe in, or both. The canister was there to catch something and allow air into the hose. I don’t get the impression you actually verified good fuel flow to the injectors. I don’t get the impression you cleaned the injectors well. Maybe I’m wrong.
 

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Discussion Starter #33
You’re correct. I’m not skilled enough to know or define good flow. Regarding the injectors, to know they’re clean, I think a professional cleaning is best. Very odd though that it ran so well yesterday in the cool weather.
 

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Just a thought here: a few years ago I bought a 750SS that had similar symptoms that you describe and some days it would run ok, others not. I traced the problem to the valve clearances - all the openers were tight and the valves were not closing properly.
 

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Discussion Starter #35
Gents the weather conditions were cool again today and the bike started without the usual difficulty, ran perfectly and idled nicely. The obvious is the cool dense air helping the lean condition. Re-winding for a second, a couple of days ago I observed and recorded video of the injector spray w throttle held open(hitting starter button plug wires detached) . I couldn’t figure out how to attach video but can tell you all it looked like a good strong pulsating mist. All in all, I’m leaning towards a reflash of the DP ecu. There is a set of db killers on the way to me, not sure if they’ll choke up exhaust flow to make a difference but I wanted them regardless, so why don’t we wait, pop them in, let’s see how it runs and go from there. I really appreciate everyone trying to help. You guys are the best.
 

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Hello RKGT- Just wanted to see if you ever fully resolved the issues you were having. Hope you are back on the road and riding worry free! Give us an update when you can!
 

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Discussion Starter #37
Metman you are the best for following up. Merry Christmas! So I did get the db killers to see if that would choke up the lean condition but it didn’t. I’m in snow country so no riding but I did buy the DucatiDiag cables and downloaded the software. I’ve yet to connect cables to the bike w the attempt to reset tps. When I do I will report back and I thank you for checking in on me.
 

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Popping is pretty normal when you’re running a high concentration of fuel additive.
 
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