GRiSO suddenly wont start (will try, stumbles, but dies)

So GRiSO was flawless up in the blue ridge mountains last week other than the neutral sensor acting up despite being replaced (new design with the regular connector, slathered in grease).

Over the weekend the hurricane moved in so bike sat outside the cabin for a couple of days in the rain and then got loaded up on the trailer and towed back. Fired up just fine to pull into garage after unloading trailer, just a few dozen yards.

Went to ride it tonight and it wouldn't start. It will try, it stumbles, occasionally it will run like crap for 10 seconds and die.

No active codes in ECU or dash. Just the oil sensor history one that comes up once a year and it didnt return after clearing it.

Looking in the fuel tank I see some small bubbles when turning ignition on (every time) but dont see anything obvious like a loose hose churning a lot of gas around when trying to start. Could the bubbles be an indicator or is it doing some sort of line clearing procedure?

Probably the drain in the fuel tank moat is clogged and water got in the gas and is now in the fuel lines.
This happened to mine. I was on a trip when this happened and I did not want to start pulling the bike apart to any great degree, so I pulled the injectors and pulsed them with Guzzi Diag injector test dozens of times till the water came out of the lines and it was just spraying fuel.
When I got home, I replaced all the fuel lines so that I could then purge the lines easily by just removing the hose at the injectors and turning on the fuel pump for it's initial prime and it would then empty all the water out which sinks to the bottom because it is heavier.
I also replaced the fuel filter and internal hoses while I was at it. I blew the crud out of the vent and drain lines on the tank too.

May of not blown the fuel hose off but split it. Pull the pump for a looksee.

Thanks Ill start digging into the fuel system. Hopefully just draining the tank and clearing the lines does it. We did get some serious sustained rain so I could see the backed up water thing.

Then Ill probably dig into the tank if that doesnt fix it. Although sounds like I need to anyway, got another response that the fuel filter can split.

These 2 threads may help you.
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Thanks, that fuel tank walktrough will be helpful. Ill probably do that change to the hoses as well internally as I have a lot of gates line around from dealing with issues on the MV.

If you don't want to deal with it or need help give me a call. Make sure it is SAE 30R10 hose.

Wet spark plug wires? Pull them off both ends and dry to be sure...

So it looks like it must have been the water issue. I siphoned all but the last few drops out and dumped in a gallon of fresh 93, cleared the lines and she fired back up. Holds an idle well, feels like MAYBE its vibrating a little more than usual but it could just be because its on the work stand.

I will still likely be shopping fuel system parts to just refresh the hoses and filter just in case since i want this bad boy bulletproof for road trips.

Now just to figure out why this damned neutral light is flaky again. Got the new sensor installed and the new clip on it slathered in grease to keep water out and it started being unreliable again (the day prior to this rainstorm).

Congratulations but if the Neutral switch is playing up you need to fix that, if the ECU thinks the bike is in gear it won't want to run.
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I couldn't find a description of the switch, is it a microswitch or just a simple contact that grounds to a protrusion on the selector shaft?
Try a jumper cable from the switch to chassis to fool the ECU into thinking the bike is in Neutral.

I misspoke and misremembered, I updated the oil pressure switch, not the neutral switch. I dont think its electrical though as i can reshift the bike and the light will go from flickering to solid, I wonder if something has play in it that is being phsyically jostled loose.

For the fuel system does anyone know the filter part #? I think GU05107430 is the gasket for the pump housing but my parts manual just kind of lists the whole pump assembly as a part and its pictured as the OLD design where mine has the recall done (shorter accordion hose and fuel filter zip tied to pump).

Ive got a ton of gates submersible line in 8m around because its what my MV uses now (also went from their brittle design to old fashioned braided hoses) so my plan was to get SS clamps and that gates hose to rebuild the entire assembly when I am in there. Its running fine but I do see miniscule bubbles coming up from the bottom so Im guessing something isnt right under the fuel filter.

SOrry to bump an old thread but realized I didnt close the loop...

So yeah, it was water.[You must be registered and logged in to see this image.]