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I have had a similar issue and it was the tank that was the cause. The inner lip had gotten bent out of being concentric. No idea how - might have been when the pump got pulled at an angle at some point. Previous owner had put a lot of gasket sealant on it to stop it. I was able to bend it back to being round using teaspoon handles and levering them against the bolt shrouds. As soon as it was true again, the leak stopped.
 
Discussion starter · #23 ·
@theapp I appreciate the offer. I'll keep it in mind. Right now I'm trying the "boat load of freakin gasketmaker" option. Taking a close look, the new tank is ever so slightly out of round on one lip, so frustrating! One other thought, I'm using a black gasket from gotham cycles instead of the offical Ducati ones, I read elsewhere that they're better. Wonder if they aren't as good as advertised?
 
Discussion starter · #24 ·
@lukemillar, looking at mine I think I have a similar issue. The original tank was defnitley bad, the new one seemed better but has a spot a little off. I keep thinking it should be good because it came off a wreck that must have been running in order to wreck. Seems if the tank was leaking like this when it was running, you'd just have a little hiroshima reenactment (and no tank to part out).
 
Discussion starter · #25 ·
Fixed

Hey guys,

I'm please to report I've fixed it, and wanted to capture the fix here. I've got the tank sitting half full with no drips as of this morning, and tested while sitting on the bike.

The problem it seems was the mating surface. I spent several hours this weekend sanding. I started by using a micrometer to make sure the tank side of the flange was close as I could get to true and round, within a half MM at all points. I spent a bit of time sanding down that surface, but had some marks I just couldn't remove. To improve that surface, I used a compound called qik steel (fuel resistant variant), that's like a putty. It's specifically mentioned as being useful for fixing fuel tanks. After allowing that stuff to cure, I sanded it down so it was just a thin layer over the original surface. I used progressively finer grade sand paper starting at 80 grit to knock down the thickest portion, and moving down until I got to 1000 grit. The surface was almost mirror smooth.

I also sanded the flange plate. I did not use the qik steel stuff on the flange plate because it was far cleaner. With the flange I started with 150 grit and again moved down to 1000 grit. I could see a reflection by the time I was done.

To install the o-ring I used the well established method of slightly longer bolts to draw the plate in. I lubricated with silicone grease applying inside the plate groove, then installing the ring and applying grease to the outside of the ring. I also lubricated the tank. In previous attempts I'd tried using silicone spray and I think it bound too much. The grease I used was actually labeled dielectric grease (I verified it was silicone based) which came in a little tube and was separate from the other lubrication products. This grease was thicker, and a little more persistent. I used no additional sealant on the o-ring.

While drawing the plate in I used longer bolts as I said above, and drew nuts in with 3/4 turns each until it was all the way down.

Parts wise, I reused my original tank since it's flange was about the same as the new (used) one I bought, and it was cosmetically way better off. I also used the flange that came with the bike. For an o-ring I used a green OEM ducati one.

Thanks to everyone who chipped in, especially Mike Schwitzer who gave me a call and talked me through the process.

Hopefully sometime this week I can finally ride the bike I bought in November. There is a slight leak coming from one of the fuel line I replaced, but I'm comfortable saying that's just a loose clamp. Next steps are to perform a valve inspection & belt change, and rebuild a fork tube. Wish me luck.
 
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