Poorly 748

It sounds like a sensor being affected by heat. As you've mentioned Maidstone I'm guessing you're in Kent? If you are give Alec a call at Ducati ProTeam in Strood. For the sake of a few quid get him to sort it out for you so you can enjoy it properly! Then get it out for a few rides with us other Kent guys ;-)

 

I had a similar issue with a SPS quite a few years ago. Soon as the bike hit about 90 degrees it'd cut or at best drop to one cylinder. Checked and replaced as much as i could think of with no luck. Just on the off chance, whilst hooked up to diagnostics it cut and i noticed the throttle reading had gone ape5hit.... Cooled the TPS off with compressed air and the signal returned to normal. with the engine off, i heated it with a hair dryer and it went ape again. New TPS resolved it and it's still going strong....
The TPS isn't cheap, it may not be your problem, but it sounds like you're losing a sensor of some sorts due to heat failure/breakdown.
I'd get it hooked up to some diagnostics where you can monitor what the sensors are doing in real time, else it'll get expensive taking pot shots at what could be failing.

 

Just had a skim through and it seems nobody has mentioned the fuel pump fuse (sorry if its already been mentioned) which is under the seat next to the relays, they can get very hot and start to melt when they get a little corroded, have a look.

 

Does it have the fuel line quick-disconnect fittings in the tank base? (may not if it's an 'e' model) if so have they been replaced with aftermarket metal fittings? because if so and the 'O' rings are not Viton then they will swell and can intermittently block the fuel flow - happened to me and the bike just stopped and wouldn't start again, disconnected/reconnected the fuel lines and it was OK again for a while.

 

As abmatt said, your patience is second to none rdw and you really deserve to get to solve this now. As for taking to a dealer, if you feel up to it I would persevere for as long as you can as deeply hidden problems are often the most expensive unless found immediately by chance or skill - a real 'Catch 22/how long is a piece of string' conundrum. If none of the latest suggestions find the culprit I have a spare ECU which may be worth a try.

 

i would deffo try that,its only a 5 min job,i had the same problem, and it was the ecu.

 

rdw748

Have you checked the fuel tank vent? an incorrectly functioning vent could give rise to the symptoms you described!

 

RDW, another possible and easy to check one to add to your list. I have a 2002 MY02 748S which a couple of summers ago on hot days started missing on one cylinder before stalling after 25-30 mins of driving. It turned out after months of head scratching to be the atmospheric pressure sensor (the sensor located by the steering damper). First clue was a perished connector cover, when I pulled the plug off it was obvious water had got past the rubber boot and had been sitting within the sensor plug socket for some time leading to oxidizing of two of the three pins and a possible moisture induced short, this was warmed by the heat from the coolant header and engine to a point where it reached a critical restance. Up till then this was the only sensor connector on the bike I had not checked and cleaned up. It seemed to do it when the radiator fan was cutting in but was not consistent. If the boot is perished it allows water into the socket which sits there and when the bike is on the side stand causes two of the three pins to get white oxide corrosion on them. Immediately obvious once the connector is pulled off and immediately fixed on mine with the connector and pins cleaned up. However the sensor was damaged by the water and was causing problems with acurate setting up so it was changed. The sharp bend in that connector's trailing lead is necessary to prevent the water issue I had but the boot failed.

 

And when it is sorted we must go for a blast. Im only up the road

 

I believe the front fairing has to come off, then the clocks. The carbon piece will then slot in from behind the bevel.Then re-fit

 

Part number is 88765.1126N, get them mail order from somewhere like Moto Rapido, it is around £50 IIRC

You will need to take the fairing off, some of these surrounds you need to unbolt the clocks and drop the surround in before refitting them. the bezels are permanently glued on place and are very difficult to remove without damaging them. Hopefully it will be obvious once you have taken the fairing off.

 

Rdw, it does exactly what it says on the tin. Specifically it monitors barometric pressure and its output is used to make an adjustment to the ecu fueling map, it does this because at higher altitude there is less oxygen in the air and to maintain a correct stoichiometric fuel air ratio and it needs less fuel to maintain the ratio close to ideal. At lower pressures or higher altitude the injectors are opened for less time. According to Fallon the range of adjustment is -8% (at 13,200 feet altitude) to +4% (at -1000 feet altitude) with the adjustments of 0-3% typical for UK and UK barometric pressures. The air and water temperature sensors have a similar effect on the fueling to correct for the varying density of air (hot and cold days) and the effect of the engine when it is at different running temperatures.
From what hapened on mine it would appear that the malfunction had the effect of reducing the fuel injection pulse which leaned up the mixture so much that the engine could barely run.

BTW you can download a free parts manual for the bike from Ducati.com and they are also freely available at various other sites

 

Hi rdw748, I hope you are getting closer to fixing the problem. I'm afraid that I only have a couple more options for you to try!!!

i have had the problem wi the air pressure sensor (and or it's wiring) on my 748, and I'm afraid the symptoms were not the same as yours. There was no relation to the temperature of the bike, it came on very erratically and in my experience led to rough running and low power unless full throttle was used.

I previously had a Laverda 650, which used a fuel injection system very similar to the 748, but probably with more parts bin stealing from Fiat! There was a very common issue amongst Laverda owners which had symptoms identical to yours, and was even backed up by the exact same part being well known to malfunction on various Fiats and even an Maserati. The part in question was the cam/crank sensor, which the Laverda had two of (think the Duc only has a crank sensor). They tend to soldier on and then give the wrong signals to the ECU when hot. Apparently there is no way of testing them reliably, so replacement with a known working one is the answer. If everything else has been checked, and fuel is getting through, this may be the answer as it will knock out the spark, the ECU not knowing when to spark.

Hope you get it fixed soon, they are fantastic little bikes.