Ducati Monster Forum

Hi,

This is what happened:

I went for a ride, about 20km down the road on a pretty spirited trip i had a couple backfires on deceleration. I had these last year, but since I got my headers re-welded and put new gaskets on the pipes it's been really tight with ZERO backfires.

Later, on the way back it start to backfire just at steady throttle more and more. Then right before it cut out, it was backfiring a lot even when cracking the throttle and it was chugging. The guy behind me didn't see anything coming out of the pipes.

I then pulled over and it died when I came to a stop. I tried to restart it, and the starter motor would not crank it over but I could hear a click and the fuel pump priming.

I thought I might be out of gas, but the light wasn't on. My buddy went to get some gas. When he was gone, I pushed it down a hill and tried to jump start it. It started and sounded pretty normal, but once I came to a stop and put it into neutral, it died again.

Then, while he was still gone the gauge cluster started doing weird things. The engine light came on, the speedo needle went up and down, and the right signal light turned itself on. Also, the immobilizer light was on steady. The temp gauge was also giving no reading, then 160 degrees, then 50, it was all over the place.

Then when buddy returned with gas, we filled it and tried again but to no avail. Then, I noticed that the headlight was really dim, and lights started going out as well as the digital readouts on the cluster. We tried jump starting it a few times, but it only turned over once every few tries and didn't start.

I started to think it was an electrical problem. Last year, my old battery cooked and I replaced it, suspecting the voltage regulator. I used a voltmeter and checked the voltage throughout the rev range, but it didn't go above about 14. Also, last year, when that happened, the battery stank and was venting. This time the battery wasn't even that hot, nor was the voltage regulator.

By the end, we just loaded it in the back of a truck and brought it back. I brought my battery tender home (1400km away) last week expecting to move, so I can't charge it. Here she is looking pretty in the back of a sweet GM truck with a 350 high output crate motor  ;D.

(http://i1283.photobucket.com/albums/a554/Alexandre_Fisher/show%20off%20pics/IMAG0860_zpsc17f8c2f.jpg)

Does anyone have and ideas? I'm really hoping this is not an expensive fix, ughh gotta insure it for the year next week and the wallet is light!

Your battery went flat.

Much the same happened to me on a ride when I forgot to plug the stator back in to the rectifier/regulator after mucking about with it.

Do the standard "my battery isn't charging" diagnosis. Charge it then check voltages at idle and when revving a little, check stator resistance etc.

Where does the stator plug in? I was mucking about the gauge cluster earlier today, and shoved everything back into place (it's a tight fit).

Nowhere near. It's under your seat on a stock monster.

My voltage regulator does not have a plug on it though. The wires just come right out of it and disappear under the tank somewhere.

Follow the wires. There's a plug for the stator, and another for the r/r output.

Exact same thing happened to me a couple years ago. Ended up being the voltage regulator.

 Na, it's the carberater!   [beer] [drink]

Broke out the voltmeter today, and the battery was showing 11.3 V ignition OFF. 11 V even with ignition ON. 9.8 V when I try to hit the starter.

Battery load test showed GOOD.

Bench test of the R/R was strange. I used the diode test and was showing about .5 OHMs between some of the input and output side pins, but I couldn't get a reading when I switched the probes around (I thought some of the diodes let current through the other way).

Continuity test between the 3 pins coming off the stator all showed continuity. There was no continuity between the 3 stator wires and the frame (or negative side of the battery).

I had the bike plugged into the battery tender for a while, and it started. Unfortunately, it only got 3 hours charge, and after starting it once, it was back to 11.6ish V. I hope to get it on the tender again (outlet not working in the garage, and it started to rain outside where it was plugged in)

Sound like the reg is stuffed.

A fried battery is a good indicator the reg is on the way out.


Some good links here to papers for checking reg/rect circuit

http://www.ducati.ms/forums/77-sport-classic/122863-regulator-rectifier-testing.html (http://www.ducati.ms/forums/77-sport-classic/122863-regulator-rectifier-testing.html)

http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf (http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf)

try changing your fuel filter, its probably clogged up with stuffs. what year is your bike/mileage?

What? A blocked fuel filter causes low battery exactly how?

OP: don't. Getting to the fuel filter on injected monsters is a fair bit of work, as its inside the tank.

Compromised smoke gasket.

What did you use as a load for the load test?  11 volts (assuming your open cell voltage test is correct) is a discharged battery.  Why would you expect a higher reading with the key on and not running?  You are putting a load on the battery without the charging system operating.  It will read less.  9.6 while trying to start with open cell of 11volts?  I'm shocked it was that high.

First make sure the battery connections are clean and tight.  Bad connections could explain your wacky numbers.   Take them apart, negative first.  On reassembly, negative last.  Then charge the battery until it reaches at least 12.65 volts.  If the battery does not reach that voltage, recycle time.  If it is a 10 AH battery at about 1.5 amp charging rate this will take about 6.6 hours, assuming your battery was indeed reading 11 volts..   Now load test.  The load should by textbook 3X the amp hour rating or 1/2 the cold cranking amps.  Now that you have a either replaced the bad battery or determined yours is still good start the bike.  You should read 13.5-14.5 volts at 3K rpm.  If not hit MonstaSR2's link.

I think you guys are reading into what I did a little too much. I shouldn't have done the load test. I'm just saying I used it on the discharged battery and it said that it was fine. I realize that that was useless because it's discharged.

I will do everything else you said.

From what he's described, the fried battery & then the testing of the reg, the reg is stuffed.

The link I gave to ducati.ms has 3 really good papers on testing the reg/rect circuit.

I did the testing above today. Yesterday I charged the battery to 12.26 V. I got back to it today and it was at 12.1 V.

The bike started easily

At 2500 RPM, the voltage at the battery was 11.9 V

Voltage between R/R output (red) and battery (+) was varying but no higher than -0.17 V

Voltage between R/R output (black) and battery (-) was varying but no higher than 0.2 V

Started engine again easily, tested voltage at the battery up to 5000 RPM and it was 11.7 V or so with no variation

Tested the resistance between the 3 yellow wires off the stator. All between 0.2-0.3 Ohms. (Strange because the document above says the resistance should be 4-6 Ohms between each of them). Is this my problem?

The next tests made no sense to me because I only have 3 wires coming off the stator, not these extra ones they're talking about.

Instead, because I was unsure, I checked the voltage on the output of the R/R (between the red and green pins). It was 10 V at idle and up to 17 V with some throttle. I didn't go higher because that seemed way too high to me. Hope I didn't fry my voltmeter.

Then I bench tested the R/R:

Top Diodes, Forward Bias: PASS: 0.559

Top Diodes, Reverse Bias: PASS: all show OL

Bottom Diodes, Forward Bias: FAIL: all show OL

Bottom Diodes, Reverse Bias: PASS: all show OL

So I'm pretty sure something is wrong with my R/R. I think my battery is alive and capable of charging, holding a charge and starting the bike repeatedly. I'm not sure about my stator... the tests asking for wires other than the yellow ones makes no sense to me.

Help with analysis?

My stator winding resistance is 0.4 ohms, so your stator sounds pretty good.

Agreed that your rectifier/regulator is probably shot. Worth carefully checking connectors though before you bin it.

Time to upgrade to MOSFET, methinks.

Stator is probably good, but try this if you have an AC meter:
At least 28 volts at 2000 RPM, 33 volts at 6000 RPM at each stator wire.

Be careful measuring an unterminated stator. The voltages are large enough to bite. Edison used your stator to kill cats, apparently.

Stupid cats  [laugh]

Is this the voltage between the yellow stator wires, or between each of them and the frame?

Between the yellow stator wires, 3 readings.

New voltage regulator installed and the running voltage at the battery is ~14.2 and no higher than ~14.5 as I rev up. Problem fixed I think!