Ducati Monster Forum

Hey everyone,

Been lurking on this wonderful forum for a few weeks while trying to fix my bike, but haven't had any luck. I figured it was time to nut up and just post my specific problem already.

Background: 2002 Monster 750ie, 1,700mi

Initial symptoms:

After a night of surprise rain (bike uncovered...), I rode to work. The bike cut out a few times when I got on the brakes hard, I figured it was just low on gas and the fuel was sloshing forward in the tank. Same problem occurred a few times on the way home that day, I filled up (almost a full tank) and rode without issue.

The next day, the bike started cutting out on my way home, and was clearly misfiring. The morning after, the bike wouln't stay running for more than 10-15 seconds, and sounded like it was clearly misfiring/skipping.

Checked the plugs the next day, and found they were white, so I suspected a clogged injector (the bike had sat for a while before I got it in april) and cleaned the injectors in an ultrasonic.

This is where shit gets weird... when I threw the injectors back in, the bike still wouldn't start, but now the plugs were wet with fuel. I thought maybe the injectors were getting stuck open, but I turned the bike over with each injector pulled out of the cylinder and saw nice little puffs of vaporized fuel, so no indication of sticking or clogging. I also used a 12v power supply to click them open rapidly and they were super responsive, no indication of clogging.

I then checked the ignition system by grounding the plugs, turning the bike over, and looking for a spark, but I barely saw anything. I verified the plugs were gapped correctly, and they were, so I assumed the plugs were bad and replaced them. No improvement...

Then I assumed the coils were both bad, so I replaced them. No improvement...

That's where I'm at now. The only other culprits I can think of are the sensors that control the ignition, and the ECU itself. I ordered a crank position sensor (or timing sensor, whatever it's called... the one down by the alternator), which I'll try as soon as it arrives. If the ECU is somehow dead, I think I'm pretty f*cked...

So, if anyone has had similar problems or has any ideas on what else I can try, let me know. I'm a mech engineer, so pretty handy, but I don't have much experience with modern bikes (my first bike and project was a '74 kawi z400)

Not an expert, but remember to set (shim) the sensor gap correctly. Other than that the rain can easily cause all kinds of problems (including yours) - similar to what people report after carelessly pressure washing their bikes [bang] 

Water around the filler cap not drained properly? Rubber hoses clogged? Blow air through from the lower end.

I'm no expert on FI bikes either, but I'm thinking there's water in the instrument cluster, or it could be a coincidence with the rain, and there's an issue with the wiring harness.

Where's KoKo when you need him? ;D

I'm going to keep the existing shim in there and reuse the o-ring as well since it's in good shape.

As for the water damage, it's hard to imagine hard rain right before these issues as being coincidence... it's possible, but not likely. The question now is if it's just a residual moisture or shorted harness issue, or a fried component due to that moisture, or maybe water damage that isn't part of the electrical system.

I'm leaning towards electrical damage because of the weak and intermittent looking spark, but TBH it's not like I've got a lab-grade test setup here.

@stopintime, If I'm going to keep troubleshooting I might as well drain the tank and hoses and rule out water in the fuel system as well.

@ducpainter the instrument cluster isn't something I've attacked yet. I was under the impression that on these older ducatis the ECU doesn't really care about the state of the cluster, it's just there to read out the data the ECU collects from the various sensors. I could be wrong on that though. Also worth checking out and ruling out.

Do make sue your fuel is good, no water, no stale gasoline, in tank fuel lines in good shape, no venting issues to eliminate those variables.  If you need in tank fuel lines they must be 30R10 or the ethanol in E 10,15 fuel will eat it.

Now to spark.  Sensor needs to have an air gap of .6-.8mm.  The smaller the better.  There is no Ducati specs for the sensor, they depend on the Mathesis scan tool.  But I can offer some general stuff.  A good any vehicle resistance spec is 50-100ohms.  My experience is when they fail they tend to read close to zero or infinity.  If you have an oscilloscope you should see voltage go from about +4volts to -4volts.   Also check spark plug wire resistance.  You want to see 5K ohms.

I'm wondering if the ol' hair dryer to the opened dash trick is relevant here. And some electrical spray to disperse moisture. Check the dash plug connector for sure.
I also would drain the fuel and check for water contamination via the fuel cap/ breather system.
Check the air filter if there were airbox mods if you think water could congregate there. Unlikely with this model, but not impossible.
Maybe blow some air at any electrical components you suspect getting a straight shot of rain.