Ducati.ms - The Ultimate Ducati Forum banner
  • Hey Everyone! Enter your bike HERE to be a part of this months Bike of the Month Challenge!

1 - 12 of 12 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter #1 (Edited)
Have a 1999 748 BiPo w/ 9,500 miles on it.

Since I got it 6 months ago I've put about 500 miles on it. Bike ran great.

Few weeks ago took it on a city/hwy ride and at 65mph had sudden loss of power as if I just took my hand off the throttle. It chugged, then idled. I turned the engine off, restarted, and she ran perfect for a few miles, then did the same thing. Repeated this until I made it home.

Things I did myself to try and fix...
-- Changed plugs (needed anyway)
-- Changed out fuel pump assembly (got one from Gothamcycles). I needed a new low fuel sensor anyway so thought this was a good time to do it.
-- Checked plug wires.
-- Disconnected ECU under seat and reconnected thinking it might be a bad connection.
-- Replaced 2 Relays in front of ECU

None of these things worked. Biked acted up again after 5 miles. Sudden loss of power with a bit of bucking and kicking. NOTE: Seems the loss of power starts occurring when bike gets hot then is taken to high speed.

Brought the bike to Ducati dealer (on trailer) and explained the situation. Figured I'd have them do a valve check and belt replacement since I had no documentation that previous owner completed. They called a few days later and said the battery terminal was corroded due to a small crack in the battery. They cleaned the terminal and replaced the battery. They took it for what they say was a 15-17 mile ride with no loss of power.

Picked the bike up this morning. Ran perfect until about 5-6 miles in... bam, sudden loss of power from about 50 mph. Turn off bike, restart and she ran perfect for 2-3 miles then the same. Repeated until I made it home.

Now what? The fact that the bike runs fine for a while after "resetting" (turning off then restarting) tells me this is an electrical issue.

Next on list??....

Replace TPS?
Replace Relays (3 I believe) next to battery.
Crank Sensor?


Ugh. Don't want to take it back to Ducati dealer. Any Help appreciated.
 

·
Come in Spinner :)
Joined
·
8,159 Posts
748 misfire and stalling

GI had a similar issue for the last 6 months or so,
Checked the cps and reduced the gap, checked ecu chip seating, checked ecu for dry soldered joints, did a continuity test on all ecu plug pins and cables right back to the relays.

Nothing helped, the tacho would go erratic and finally the bike would start to misfire and then die but mostly would start right back up again but eventually got worse and would hardly run.
I found if I pulled up on the ecu plug it would run ok though.
So dismantled the plug and cleaned every oin on the ecu and socket but no better.
Finally in desperation using a pair of long nosed pliers I carefully bent each and every pin in the ecu socket down a few degrees.
Guess what? the problem went away, the bike ran perfect for the first time in 6 months with a solid tacho needle with no fluctuation which was there from when i first got the bike 9 years ago.
Done hundreds of fast miles since and the bike has never run better.

davy
 
  • Like
Reactions: draganc

·
Registered
Joined
·
16 Posts
Discussion Starter #3
Thanks Davy. Replacing the ECU was on my list as last resort.

I will definitely try this and let you know.
 

·
Registered
Joined
·
1,200 Posts
Do the dash lights go out when the bike dies while riding?

First, I recommend the famous pre-emptive fix of the sidestand kill switch bypass - possibly post-emptive in your case.. I did one of these roadside and it got me home after similar symptoms as yours. Note that the dash lights didnt go out as the engine cutting-out symptom arose.

Next maybe open up and check contacts in your kill switch on the handlebar. then check your ignition switch. Especially if the bike's been in corrosive Florida air for long, but even if not. Last thought is the coil - I've read they can go out intermittently, and possibly as the engine heats up. Possibly more knowledgeable Listers can advise?

It's a pretty old bike at this point and the wiring connections, relays and switchgear points of connection get dirty, corroded, resistance rises, electrons go rogue.
 

·
Registered
Joined
·
16 Posts
Discussion Starter #6
Update. Pulled the ECU and did what Davy had suggested.

Also did a complete coolant flush and clean with vinegar/water solution.

Started the bike and let it get to running temperature which by the way is about 15-20 degrees cooler than before. I knew it was due for a coolant change/clean but when the Ducati dealer said the coolant was way low it raised eyebrows. There was also a lot of build up around the filler cap which made me think maybe by water temp sensor was an issue..

Anyway, took the bike on the same run as the other day when I got the loss of power symptom. No problem. Did the run again. No problem.

Perhaps I should have done one or the other fixes (coolant vs. ecu tabs) independent of each other and tested the bike to really pin it down but I figured the coolant flush was very likely not going to fix the problem. Is that right? If my bike is running 15-20 degrees above normal could that have caused a loss of power with no warning?

I suspect the ecu tab adjustment as Davy suggested may have resolved my problem. Will go on longer ride and update later.

Thanks for the help.. crossing my fingers.
 

·
Registered
Joined
·
16 Posts
Discussion Starter #7
Just put it thru test 2. It sat at idle in the garage until reaching temps to trigger the fan. With it nice and hot I took a 2-3 mile run... punching it a few times. Ran perfect. Test 3 will be a longer run.

Juiced that this may be resolved.
 

·
Come in Spinner :)
Joined
·
8,159 Posts
Good to hear it's running better.
Is the temperature really that different or could it be the gauge is reading lower now that the sender connection to the ecu is making a better contact?
 

·
Registered
Joined
·
16 Posts
Discussion Starter #9
During the second test I let the bike sit longer at idle and it did get back up to the 220 or so range but seemed to cool down much faster at speed. The reason I don't think the coolant change made a difference re: the loss of power issue is because the problem was occurring when the bike was thoroughly warm but not super hot. Had the bike lost power at only super high temps then maybe it would make sense.

Still thinking the ecu adjustment may have done it. Retracing my steps a bit I do remember removing the ecu to thoroughly clean under the seat. Perhaps disconnecting the ecu created a weak connection after reinstalling. Still crossing fingers until I go on a long, more intense ride.
 

·
Come in Spinner :)
Joined
·
8,159 Posts
Mine would do it after about 3 or 4 miles of running, cold it would be fine which is why it took me so long to fix it as roadside is a lousy place to diagnose electronics.
I tried getting it hot at home but I suspect with no load there is very little heat under the seat from the exhausts to cause expansion and contaction of the ecu plug terminals.
My first real clue was when I pulled up on the plug roadside with it idling badly and it would either stop of run ok depending on how much preuure I applied.
I finally got it home the last time by jamming a roll of insulation tape I carry under the plug, held up by the tension of the ecu rubber mounts.
I could always tell when it was about to start acting up as the tacho reading would start to go erratic then the motor would falter.
Since I did the pin trick I have the most stable tacho needle I've ever had in the 9 years I've owned this bike.
 

·
Come in Spinner :)
Joined
·
8,159 Posts
Why wouldn't you ?
 
1 - 12 of 12 Posts
Top