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Discussion Starter #1
Lost in the delusions of my own grandeur I decide to sell a perfectly working jap bike and buy a ducati (2000 996 biposto)... that's in a box...ok, actually two boxes and the rolling frame with the crankcase still attached. I knew it was going to be a work on it hear and there, buy parts when funds became available, first ever working on a duc, yada, yada, yada... I gave myself a year to get it going but it only took six months. Good.

Now for the bad part: I was headed for work on it and after making a left turn she decided to die on me. Pulling off in a parking lot I noticed immediately that the fuel pump was no longer priming. Not a huge issue I thought since I knew that the low fuel sending units wires were not in the best shape, I figured the pump must have been grounded out. So I ordered a new sending unit and stopped off at Autozone for a fuel pump (94-95 Ford Mustang GT is the same except for the bottom plastic piece) and go ahead and get another new fuel filter since I'm going to be in the tank again. So I change out the sending unit/pump/filter button it all back up and whatdoyaknow? the pump is still not priming. Bike turns over with the starter but no go (obviously). So I get down to business checking fuses (all good), relays- both undertails and main ignition (good), and the handle bar switch (good).

Somehow I get to playing around with the ol' multimeter and found out that with the ecu plugged in the fuel/ignition circuit only has .5V going to it. Now I'm pissed because it seems my new (to me) ecu is fried. So biting the bullet I purchase a ecu off of fleabay. New ecu arrived and did not change the symptoms: with the ecu unplugged and the fuel/ignition relay jumpered I have 12V for their circuit but with the ecu plugged in it drops to .5V. At this point I'm looking at replacing the whole dang harness since I have tried unplugging every other component looking for one that was shorted. The only lingering thought is that the sidestand cutout switch which is not on the bike- heck I can't even find it on the schematics... Anyone out there REALLY know the ducati electric system?
 

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I don't know the electrics too well, but from memory doesn't the bike just prime until the injectors have pressure? i.e. if it's standing & not running it will run the pump for a few seconds and then cut off?

I'd assume from what you've said that the "cut off" is therefore coming from the ECU (0.5v) so the ECU is getting a signal saying that the fuel lines are pressurised?

As I said though, I haven't delved that much into the mysterious world of Duke electrics......
 

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Ready to kick yourself? I'm pretty sure its one of the two cube-shaped relays under the seat. Ducati wants $35 each and god knows when the Italians will decide to put down their espresso and ship 'em out. Instead, take one to NAPA (the auto parts store, not the California wine region) and buy the Chinese made equivalents. They will be in stock and...$8 each.
 

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Discussion Starter #4
Thanks for the quick reply

neejah- on a working bike whenever the handle bar switch is closed (run or what have you) the fuel pump comes on then stop. It's not doing any of this.


nine16- Both of the undertail relays are fine (I would never be that lucky). The fuel injection/ignition relay closes when the ecu is plugged in and that's when I'm getting the .5V at the fuel pump. With the ecu unplugged and the relay jumpered then and only then do I get my 12V at the fuel pump.
 

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I went through the exact same thing and, with the exception of replacing the fuel pump, followed your path to the T. Even went as far as replacing the relays etc. Chances are your under seat relays are fine. Testing them is easy though; trigger them and test continuity with your multimeter. I can't exactly remember which pins do what off the top of my head, but the schematic should be stamped on the side and Google is your best friend. I'm thinking the 5v is right for that circuit, so I wouldn't worry about that. On the right side, one of the relays in the group that contains the flasher relay is responsible for triggering everything else. If it doesn't fire, the relays under the seat don't trip, the pump doesn't prime and you know the rest. That relay looks similar in size and shape to the ones in the rear, but is lacking a fifth pin. Good chance it's a dingy yellow color. Test that one the same way you do the ones in the rear. The continuity seems wrong (at least it did to me), but if you're getting it it should be right. If your relays all test out, get some electrical parts cleaner and give all the contacts a good cleaning and see if that helps. If not, you might just have a short somewhere. After going through all that myself, and picking up some grey in my goatee, it turns out I have something of a short in or near that block of relays. The relays all test fine, but every once in a while I can flip the key and the pump will not prime. I can pop out a couple of Dzus clips, wiggle the relays and the pump primes right up. Hope that helps. I know how frustrating it is.
 

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Discussion Starter #6
Mainframe- Thanks. Good to hear it's just not me! I'd be pretty happy to see 5V but unfortunately all I have is .5V :( ... I've check the main ignition relay (the one by the battery)- went to far as to remove the cover to watch it close.

Please keep the suggestions coming- I'm about to turn her over to a dealer!
 

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Thanks for the quick reply

neejah- on a working bike whenever the handle bar switch is closed (run or what have you) the fuel pump comes on then stop. It's not doing any of this.


nine16- Both of the undertail relays are fine (I would never be that lucky). The fuel injection/ignition relay closes when the ecu is plugged in and that's when I'm getting the .5V at the fuel pump. With the ecu unplugged and the relay jumpered then and only then do I get my 12V at the fuel pump.
Ah, OK.......check the continuity across the cable from the relay to the fuel pump, I'm assuming that the relay closing is sending the 12V to the pump (although I'd check that first) - I had this happen on an old Alfa, the FP relay was clicking, but the contacts were that bad that it wasn't passing the current to the FP - although the voltage was registering 12v.....

Neil
 

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Hmm... One thing I forgot was you may have a bad ground. Have you checked your ground connections for resistance? I had a faulty ground in the ECU that would't let me rev past 5K. It would just bog out. Anything under that and it ran fine. It's not completely impossible that the ECU you bought off of ebay has the same short. I want to think I read somewhere that the 1.6 was prone to flaking out. A little reflow soldering may be in order. Just pull your EPROM so you don't risk cooking it.
 

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Discussion Starter #9
Neil- I actually have a bunch of the undertail relays- old and new (it cross references to a GM part). When I do jumper the relay I end up with 12V at the FP.

Mainframe- The only way that I can think of to check the ecu's ground is to pull apart the connector- which I've thought about but have not done... yet.
I've heard of people baking their ecu but have been reluctant so far. It just really wouldn't explain the hard fail the circuit (at least in my mind). Since I do have three ecu on the bench I guess I could give it a shot- what temperature and time are you baking it for?
 

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Neil- I actually have a bunch of the undertail relays- old and new (it cross references to a GM part). When I do jumper the relay I end up with 12V at the FP.
So the pump runs with a jumper over the FP relay? (So the wiring to the pump can be assumed to be OK.....)

If so, what is the switching signal doing at the relay? i.e. is it getting one?.......I'll scurry off to have a look at the diagram after dinner if I can find it...
 

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.....scurried off to check wiring diagram, and remembered I'd given the manual away when I sold the 916 in April......d'oh!
 

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If you're not fully grounding, that could be causing you to get a lower voltage reading. If you look at that schematic, pins 34 and 17 are the ground for the FP and starter relay.

Ok. Try this:

Check to make sure you're getting 12v to the starter relay. Then check to make sure your ground from the starter relay back to the ECU (pin 34 or 17) is clean. If those both check out and you're not getting 12v to the fuel pump you have a bad ground in the ECU.

The general recipe for baking a PCB is 20 minutes at 400 degrees. I was a bit leery of melting some of the random plastic parts in the ECU housing so I went a different route. I pried off the cover and removed the EPROM. Then I used a heat gun on high and heated the board that way. I focused the heat where the riser pins go from the PCB to the harness connector sweeping back and forth so I didn't burn anything up. When you see flux starting to bubble around the solder joints and the solder turn silvery, it's done. Place in windowsill to cool:p. A tube of black windshield sealant from the autozone will serve to glue and seal the lid back on.
 

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Just thought of another "wow I felt stupid" moment. Have you tried charging the battery? Yeah, I know it sounds stupid. That's what ended up being the problem when my pump wouldn't prime. At one point I had even bought a new battery when I had seemingly run out of options (swapped relays, traced/tested wires etc.) and had ran my battery the rest of the way down trying to start it. After getting the new battery, everything worked again. I was a genius! The next morning...same old crap. The lead acid battery had enough juice when I first hooked it up, but needed to be fully charged which I neglected to do. Somehow, even though it wouldn't push enough current to get the fuel pump going, it would still turn the starter over. After procuring a battery tender and letting it fully charge it never gave me another problem. Well, other than having to occasionally wiggle some relays. So after days of mucking with it, buying and returning countless relays, tearing the o-ring for the fuel pump assembly and buying a new battery, all I ever needed to do was charge my battery.
 

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Discussion Starter #15
Neil- with the ecu plugged in an the handle bar switched on and off I can actually and feel the relay closing.

Mainframe- I have thought and read on countless posts (I have searched ALOT) about the batteries being a weak link. Since new I have kept it on a battery tender (even though I've heard bad things about them) and even took the batter to the autoparts place up the street to have them test it and they said it was fine. Also a bad battery shouldn't account for a lose of power once going, right?
 

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If you have a bad connection between the stator and rectifier, or either of the two has gone bad, it could die on you once the battery goes down. Same principal as when the alternator dies in your car.
 

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Neil- with the ecu plugged in an the handle bar switched on and off I can actually and feel the relay closing.
That's a little odd - if the ECU is triggering the relay (which is then closing), and if you put a jumper cable between the pins on the FP relay it runs.....then there isn't any reason that it shouldn't run when connected?
 

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I've check the main ignition relay (the one by the battery)- went to far as to remove the cover to watch it close.
But are the contacts good? when mine failed it would switch mechanically but the contacts were oxidised and so current wouldn't always pass through, also there are two output contacts on this relay that are the same (NO) rather than a change-over relay with NO and NC contacts that you normally find - I trust you have the correct type?
 

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Discussion Starter #19
Neil- it won't run with the relayed jumpered (and the ecu unplugged) but it will allow the 12V to be passed to the FP

Dukedesmo- I hadn't thought about the main relay since I saw it closing... I'll try swapping it out just to be safe.
 
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