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After replacing the fuel filter and the thermistor for the low-fuel light, and installing a new o-ring for the flange that attaches the fuel pump to the bottom of the tank, I've got a new problem. Specifically, a fuel leak. When the bike is being stored.
The strange thing is that if I run the bike for 5-10 minutes, there is no leak. But if I shut it off, and wait 15 minutes or so, it will start to leak. On this model Ducati, there is a large plastic cover that protects the quick-release fuel line connectors. With the flange cover on, you can't really tell where the leak is coming from. So I took the cover off to investigate. The first thing that I noticed was that one of the bolt bushings for the cover has become elongated, and is no longer flush with the rest of the cover:
The flange is attached to the tank with 6 (I think) bolts. 3 of them attach the flange to the tank directly, and the other 3 attach the cover to the tank and go through the flange. In other words, the cover being attached helps seal the flange to the tank. So a bent cover might be a problem, but I don't think it's my problem.
I pulled the cover, and the tank seems pretty straight:
(The gooey stuff is petroleum jelly for the o-rings.) Because some of the cover bolts are longer than others, and the holes in the tank are blind, I put together some washers to simulate the depth of the cover. That way I could use attach all six bolts to the tank without the cover being in place. Here's how it looks installed:
The torque measurement for those bolts is only 5Nm. You can see from this photo that the flange doesn't appear flush with the bottom of the tank. I think the photo makes the gap look a little worse than it is, but still, it's not flush. There's also no gasket sealing the flange to the tank -- there's only an internal o-ring (which I replaced).
I reinstalled the pump assembly, started the bike and no leaks. 5-10 minutes later, it started leaking slowly. If you look at the bolt in the top of this picture, you can see that it's wet with gas:
You can't tell by the orientation of the photo, but that bolt is the near the lowest point in the tank, so it makes sense that that's where I'd see a leak.
I don't know how to progress from here. The bike only has 8,000 miles, give or take, and so I find it hard that the tank is warped or needs replacement. What do you guys think? Ducati have had a problem with plastic tanks warping and swelling, so this could be the same issue, but the bike is 10 years old and I don't expect any help from Ducati NA.