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Discussion Starter #1
Hello all,

I'm a new poster to this site, but have been lurking for a while. I was prompted to post in hopes of getting some help from the great hall of wisdom here for m 748.

It's a 2001 748S. What's happening is (for no apparent trigger) it will lose power no matter whether while full on open throttle, or just pulling away at a light. To me it feels like the fuel flow is being restricted down to almost nothing, very sluggish throttle, slow reponse, no power, and then will usually end up stalling out. After this, it doesn't usually want to restart for a little while. At first I thought bad gas, dirty injectors, clogged fuel filter (replaced fuel filter and plugs, ran Heet through a tank of fresh fuel)... But it now seems to be related to water, pointing me to electrical. The first time it happened the day after washing the bike (not using a hose), and yesterday it happened later in the day after being caught in a downpour on the way to work.

Does anyone know of any particular electrical part that's susceptible to water that would cause these symptoms? I'm sure the problem itself is minor and small, but troubleshooting electrical is far from my strong point. Another thing that seems to be happening is that the battery is losing charge, hence the not wanting to start. This would point me to perhaps the short being somewhere in the charging system?

Any help, pointers or suggestions would be greatly appreciated!
 

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I had very similar issue, mine happened to be a bad crank position sensor. However, many things can cause similar issues, such as fuel relay starting to go out, fuel pump itself (unlikely), happened to have both could starting to act up (extremely unlikely but impossible), etc.. There is a recent thread about other people having same issue that was updated in last 3 days.

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Hello all,

I'm a new poster to this site, but have been lurking for a while. I was prompted to post in hopes of getting some help from the great hall of wisdom here for m 748.

It's a 2001 748S. What's happening is (for no apparent trigger) it will lose power no matter whether while full on open throttle, or just pulling away at a light. To me it feels like the fuel flow is being restricted down to almost nothing, very sluggish throttle, slow reponse, no power, and then will usually end up stalling out. After this, it doesn't usually want to restart for a little while. At first I thought bad gas, dirty injectors, clogged fuel filter (replaced fuel filter and plugs, ran Heet through a tank of fresh fuel)... But it now seems to be related to water, pointing me to electrical. The first time it happened the day after washing the bike (not using a hose), and yesterday it happened later in the day after being caught in a downpour on the way to work.

Does anyone know of any particular electrical part that's susceptible to water that would cause these symptoms? I'm sure the problem itself is minor and small, but troubleshooting electrical is far from my strong point. Another thing that seems to be happening is that the battery is losing charge, hence the not wanting to start. This would point me to perhaps the short being somewhere in the charging system?

Any help, pointers or suggestions would be greatly appreciated!
Do you have a voltmeter? And if so, can you start and idle the bike and take some readings for us? That would help.

Also, any chance on pinched fuel lines or split fuel lines in the tank at the filter?
 

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If it's any incentive for you all to pick your brains some more, duc canuck is a bodacious babe!
 

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Discussion Starter #6
Do you have a voltmeter? And if so, can you start and idle the bike and take some readings for us? That would help.

Also, any chance on pinched fuel lines or split fuel lines in the tank at the filter?
No chance on pinched fuel lines, or split lines at the filter, I had that all apart and inspected it all already. I would have to say though, that the quick disconnects are complete shite. I replaced those with stainless already...

I don't have a voltmeter, but I can get one. Not certain on the bike idling long enough for me to get readings though. What would I be testing?
 

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Check the O rings in the quick disconnects haven't swollen and partially blocked the lines.
Some aftermarket disconnects don't come with nitrile rings.

.
 

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No chance on pinched fuel lines, or split lines at the filter, I had that all apart and inspected it all already. I would have to say though, that the quick disconnects are complete shite. I replaced those with stainless already...

I don't have a voltmeter, but I can get one. Not certain on the bike idling long enough for me to get readings though. What would I be testing?
basically I'd walk you through some steps to see if the charging system is working ok. It's real simple, but you'd have to have a meter that reads dc voltage first. If it's not the charging system, at least you'd have that out of the way.:)
 

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Stuff to check:

- Voltage at the battery and while running to make sure the charging system is ok

- As mentioned if you have aftermarket metal fuel connectors there is a chance the internal o-ring has swelled and is blocking flow.

http://www.ducati.ms/forums/80-hall...k-quick-disconnects-internal-o-ring-size.html

Then electrical - take apart the connectors and check for corrosion or water entry. Look for obvious stuff like loose connections or exposed wires. Put them back together with dielectric grease.

- Ignition relay (the yellow one sitting next to the battery)
- Kickstand relay (one of the small black relays, mounted with the yellow one. You can swap the two and see if it makes any difference. The other one is for the radiator fan)
- Fuel pump/engine management relays (the two that are directly under the seat)
- Kickstand switch/bypass wiring
- Coolant temperature sensor
- Crank position sensor
- Atmospheric pressure sensor (the one next to the ignition mounted on top of the coolant bottle)
- Connection at the ECU and the EPROM. Check the condition the ECU ground wire (it comes out of the wiring harness and bolts to the ECU housing).

My advice is to go to a dealer than has a Mathesis/VDST program to check the computer codes. I chased a gremlin like yours for 6 weeks with no result. Put it on the computer and it gave me a crank position sensor error code - bingo, new sensor fixed the problem. If I had done that first I would have saved myself a lot of wasted time.

Good luck! Too bad you aren't still in Canerduh, I try to help out locals whenever I can. I assume you are from the Great White North based on your name :D
 

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Discussion Starter #10
What a fantastic list of stuff!! I will be filing this away for possible future problems..
I have now located the problem. I think.. The two connectors that are on the wires coming from/going to the regulator-rectifier were completely cooked, not to mentioned that one of the wires was completely corroded!! I hope this solves the issue, but if it doesn't, at least it's fixed, because it was clearly not a good thing.
Thanks so much everyone for all the ideas and help, all very helpful. It was just a matter of resigning myself to starting to pull apart the electrical system. Not a happy thought for me.. But I'm glad I did and was well rewarded with an obvious problem right away.

Good luck! Too bad you aren't still in Canerduh, I try to help out locals whenever I can. I assume you are from the Great White North based on your name :D
And in answer to the above quote, yes I am from Canada, NS actually. Just relocated in December. And here I thought my girl would be so happy with the change of climate. Just goes to show me!! :rolleyes:
 

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Aha, makes sense. Once you fix the RR wiring be sure to check the voltage at the battery at idle and up to 3000-4000 rpm to make sure its charging ok (and not overcharging, it should never be higher than 14.5 v or so).

NS eh. I'm from Moncton, NB and went to school at STFX before I moved to Montreal. Used to spend a lot of time on the Cabot Trail when I wanted to escape from classes :) I miss the Cape Breton routes, and the coastal roads around Antigonish.
 

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For what it's worth this is the best way I've found to fix the alternator cable joint. Will carry massive current and can still be easily taken apart.
 

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