docc

The TPS can be checked on or off the bike with an Ohm meter by watching resistance as the TPS is very gradually opened and closed. If the resistance jumps suddenly, the TPS is bad. I could not find my bad TPS with the mV readings, but the resistance method showed it clearly.

13V to 11V is a big voltage drop. Mine only drops 0.5V. Something (likely more than one thing) is up. Let's work through it. One thing at a time. I'm a big fan of the MAXI fuse conversion for the 30amp main. I would also replace all the fuses in the block with the correct amperage. if they blow, there is something wrong (shorted) in that circuit.

This is the very best answer and source (in North America) from Kiwi_Roy posted in Relay Replacement.

Hi! Yeah just back from Barber's Vintage Festival. More on that later . . . Here's the post on the MAXI fuse - no more trouble after that installation, but again, even the holders I added externally for the standard fuse melted or burned off with out blowing the fuse, I wish i could remember where I got the MAXI holder (thought it was O'Reilly's).

Wow, yeah! Full black exhaust - never seen that before! Nice!

Onibaka in Belarus. Konstantin, no?

I think I may have dated a large drum controller in college . . .

True that. As gs taught me: even the copper paste is still an insulator/ non-conductive. Beyond that (and even more worrisome), the silicon in dielectric grease chemically turns to something like glass on or around any contact points (i.e. relays). It can infiltrate the wiring in this state for a significant distance. We can all imagine what a coating of glass would do for the conductivity especially on contact points. Glass is one of the best insulators. I'll get back to my "Maintenance Checklists" and amend them. Thanks for expert reminder guys!

Those aren't terrible voltages: this is do-able! I didn't look back through all your posts, but 1) ground the regulator case to the timing chest. While you're at it, ground the timing chest to the spine frame. 2) make sure your battery terminal stack is clean and tight. 3) inspect the 30 amp regulator fuse for signs of funkiness. Two questions on voltage: What is your voltage key on (not running)? and what rpm are you referencing "throttle open/throttle wide open?"

Certainly, it's time to set the voltages straight which is looking like a battery to begin with. Yet, alot was apart and back together and it was "running great" before . . . Today my son and I worked on his vintage bike getting ready to ride to Barber's Vintage Festival. Simple stuff: check to be sure the petcock had good fuel flow both "on" and "reserve" (it did), and replace the spark plug caps with known good ones. Bike would not start. Not start. NOT START. A couple hours going over everything, taking things apart, leaving for lunch and coffee. Once back and checking for (no) voltage at the points: there it was up under the tank - the points connector had come undone while fiddling with the petcock. There it is again: "Don't fix too many things at once!" But also, czakky, once your voltages are good, you may need to go back over the harness under the tank and under the airbox simply looking for something not plugged in. Very carefully inspect all the wires that got hot in the meltdown to be sure they are not shorted to ground or broken/ burnt open. Don't give up! I've got too much beer riding on this (even if I do have to split with K_R and gs. And Hubert, of course . . . )

czakky and I are thinking it's time for a good battery test, maybe new battery. Then we'll test the regulator after it is grounded well back to the engine. A short like this can cause some havoc, but nothing craft beer cannot fix!

Hubert, Moto Guzzi replaced both my side covers and starter cover under warranty, but my dealer made me promise not to put them on. So, I've fiber glassed the backs of all three of the body parts on the bike and still have the new pieces in the bags. The cracks are just there for looks. Otherwise, C-zak: 11.9 V is pretty much a dead battery. You could try charging it and seeing if this changes the run condition. That short had to be pretty hard on the battery. Maybe the regulator too. What does the black wire look like going into the right side top of the regulator? Most important is Hubert's question about the main ground cable. I can almost see it in your photo from when the airbox was off . . .

There are some replacement mounts available for the coil mounts from Touratech. When you replaced the timing sensor, you are certain it seated fully and everything got plugged back up? This doesn't sound like TPS at this point. The two nipples on the bottom of the tank each get a small hose that drops out behind the gearbox (one for tank vent sometimes has a small one-way valve in line, and the other for tank over flow). So, what does the bike actually do? crank over, fuel pump primes, starts and stalls?

All about right except docc didn't solve the mystery. Kiwi-Roy to the rescue, and gstallons who also saw this for a bad connection. Makes perfect sense (now) that the starting was seeking a new ground path that couldn't take the juice. The main ground strap is a little hard to see, but look under the seat release at the back right of the gearbox and the terminal should be visible:

They look to the best of what Moto Guzzi is building. A very nice choice and really good all around motorcycle! Excellent choice!

I could be asking the wrong questions. But, there's no doubt that melted black wire is trouble. And we know it went to the negative side of the battery. So, where did it go forward from there? Had to come from somewhere . . . The other end of the wire?

The good thing about continuity testing is you're using 1.5 volts from the Ohm meter and it leaves very little smoke to get out of the wires. The question about your melted black wire is: where did it come from on the front of the bike? Is it the regulator ground?

C'Zak: Just to be sure: when you traced the bad wire to the battery, it went to the negative side for sure? The picture looks like a black wire form the factory harness (not an add-on from the PO). Can you confirm this? If so, my schematic seems to only show black ground wires from the headlamp and the regulator. And one big, short one to the back of the gearbox. Some continuity testing using an ohm meter with the key off might be a good idea to find what is connected where. Most of us would not use a black wire to power positive to a vehicle device, but . . . ?

But that ground . . . I'm thinking of it as coming back to the battery. But from where? The regulator? Maybe the headlight? That will be where the short likely began. And what about The Mystery Ground? What was that wired to?

So, the ground actually was from the regulator? It's just that you can't actually short a ground to the frame. So, if there wasn't a hot wire melted into it, I would think the regulator played up and shorted itself through the ground wire. 1) Is there a separate ground to the regulator case? 2) What does the green 30 amp fuse and its connections look like? 3) You could mention the two lovelies at the bank to the wife and probably get of of dinner plans.

c-zak: post your voltages across the terminals: key on, idle, 2500 rpm . . .

Grounding is known to be rather lacking in this design so, yes, there are grounds running the length of the wiring harness back to the terminal stack on the battery. The black one may be from the regulator. The white is power to the Run Switch from the middle relay and only energized when in neutral. Your trace will tell for certain. No doubt you're onto the culprit!

I didn't do any readings above 4000. With no accessory load, the 14.2 volts is steady from 2500 to 4000. Better not check it tonight - she really howls down here in the basement on the lift as the revs climb!

Key on : 12.74; idle: 12.56; 2500 rpm: 14.2. Jacket and gloves on: idle: 12.25; 2500 rpm: 12.65; 4000 rpm: 13.0 77 watt jacket only at 4000 rpm: 13.5.

Hubert , " P / A / S ?"