Ducati.ms - The Ultimate Ducati Forum banner

1 - 20 of 20 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1
Hi there,

I'm new to the forum, hope I'm asking this in the right thread. Need some advice here.

I've a 1995 916 Senna and have had fueling issues haunting the bike for months now. After numerous visits to my mech, and trying different solutions, the problem seems to go away, but always returns after a while.

The problem:

Under normal riding circumstances/condition, the revs suddenly begin to gradually drop. Giving it more throttle doesn't bring the revs back up. I can slowly bring it back up by shutting the throttle and gently bringing it back up, but it won't rev beyond 5,000rpm. Attempting to do so will result in the bike jerking as thought the ignition has been abruptly cut. Restarting will only temporarily cure it before the problem returns. Curiously it happens on some rides. Some nights and some blazing hot days I can take it out for a short spin and theres no issues and next ride the fueling gremlins strike back.

Attempts to cure:

Changed new spark plugs
Disconnected the PC
Tidied up some wiring to the rectifier
Serviced fuel pump and filter


Any ideas on what is causing this? Would appreciate any feedback. Thanks!
 

·
Registered
Joined
·
654 Posts
If the fuel filter and hoses are all ok internal and external,
plus the O-rings in the quick disconnects are the correct type
viton etc, not swollen stopping fuel getting through.
It sounds like it could be the crank position sensor starting to give up.
 

·
Registered
Joined
·
2,050 Posts
Change your engine temperature sensors before you check the CPS.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #7
Thanks guys, I'll give it a shot and update here. Appreciate the advice!
 

·
Registered
Joined
·
10 Posts
Discussion Starter #8
That was the issue with my bike - ECU coolant temp sensor was a bit wonky. Wells part # SU4122, which can be sourced from Autozone.

John
Hi there John,

If you don't mind could you elaborate on what happened when you had the problem?

Thanks!
Jules
 

·
Registered
Joined
·
2,050 Posts
Ditto. Drove me nuts. Only happened when the bike got up to operating temperature. In my case giving any more than a smidge of throttle caused it to cut out like you were hitting the limiter. Had to ride it back from NYC to Montreal like that.

That was the issue with my bike - ECU coolant temp sensor was a bit wonky. Wells part # SU4122, which can be sourced from Autozone.

John
 

·
Registered
Joined
·
10 Posts
Discussion Starter #10
Ditto. Drove me nuts. Only happened when the bike got up to operating temperature. In my case giving any more than a smidge of throttle caused it to cut out like you were hitting the limiter. Had to ride it back from NYC to Montreal like that.
Yikes! What a nightmare. Glad you made it back alright. I almost got run over by a 16-wheeler when the problem kicked in while going uphill on a highway.

One attempt to pick up the bike after the mech told me it was fixed, I had to turn around not once, but three times. When my mech haves a go, she behaves herself. When I try to take her home, she throws a fit. I think my bike likes my mech much more than me.

I tried to take her our for a spin last night but the problem has gotten worse. The fueling went off just after a few hundred meters.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #11
Hi guys, just to update.. got the bike back after a while as my mech and I have been busy.

Fitted a new temperature sensor and went for a long run and the bike did not miss a beat! Fingers crossed the fueling gremlins have finally been cured!

Thanks once again for all the help.

Cheers!
 

·
Registered
Joined
·
2,050 Posts
Told ya. :D

Glad it is fixed. Fuel injection issues are frustrating. I just went through another ordeal (crank position sensor failed) that had me scratching my head for a while.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #13
Told ya. :D

Glad it is fixed. Fuel injection issues are frustrating. I just went through another ordeal (crank position sensor failed) that had me scratching my head for a while.
Thanks! Ah yes, I was told that the crank position sensor may have caused the issue. Will keep that in mind. After more than 6 months with a grumpy bike, the first proper ride was satisfying, even in the rain!
 

·
Registered
Joined
·
153 Posts
Hi guys, just to update.. got the bike back after a while as my mech and I have been busy.

Fitted a new temperature sensor and went for a long run and the bike did not miss a beat! Fingers crossed the fueling gremlins have finally been cured!

Thanks once again for all the help.

Cheers!
Maybe Im nutz but I would think your mech would know this before you throw up a SOS on the intraweb and find the solution.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #15
Maybe Im nutz but I would think your mech would know this before you throw up a SOS on the intraweb and find the solution.
Well, I was kinda desperate :(

My mech has been trying to troubleshoot by clearing suspected causes (fuel pump and filter, plugs, wiring etc which had issues of their own and probably contributed to the problem) When he's done, the bike runs well for a while before the problem returns. He's not familiar with the temp sensor problem. Ain't no Ducati specialist but he does have a 748R.

Official Ducati dealers here don't have much know-how regarding older models, and the ex-staffers who do are hard to track down or can't pinpoint the cause. Even consulted people from the local Ducati club, but the problem with the temp sensor seems to been uncommon here?

To give a bit of perspective, the superbike community here is not very big, what with us having to pay up to twice the price for our big bikes. (Panigale is about 46k USD, Desmosedici 170k USD) Japs are cheaper but still damn expensive.
 

·
Registered
Joined
·
2,050 Posts
To be honest it isn't an "obvious" solution unless you have experienced it. Most techs would assume that if the sensor goes out it will go into a fail-safe map and continue running relatively well. But that is not the case with the temp or atmospheric pressure sensor (I think it is for the air temp sensor).

Try unplugging the sensor and then running the bike. You will very quickly see it does not go into a failsafe mode. It runs terribly, if at all.

VDST software is handy for tracking down these issues, it will throw a code when the readings go out of whack or if there is a short/open circuit. But not everyone has access to it.

Techs are only as good as their personal experience. If they never encountered it before, they likely will have a hard time diagnosing it. It says nothing in any of the service manuals about the behaviour when these sensors fail - in fact the troubleshooting charts usually omit them, they say basic stuff like "sputtering on acceleration - check fuel filter, fuel lines, vapor lines, spark plugs, air filter"
 

·
Registered
Joined
·
803 Posts
speaking of VDST - Has anyone done a DIY version of the "checklamp" -thing that connects to the three-pole connector near the ECU, to check error codes from the ECU? Is it just a lamp between two of the connectors, or is there some high tech stuff involved (which I doubt..)?
 

·
Super Moderator
Joined
·
8,212 Posts
To get back to the first question.. I think I may have a DIY build instruction for the testlamp.. Got it off speedzilla i believe. You could try searching there.

Ended up not using it since I pinpointed my issue as being the ECU (P8)
 

·
Registered
Joined
·
153 Posts
Glad you got her up and running:D
 
1 - 20 of 20 Posts
Top