A funny thing happened on the way to fill up today. The gas cap would NOT come out of the filler hole. It appears that the black rubber/plastic thing has expanded for some reason and would no longer fit thru the hole. I had to come home and remove the filler assembly in order to squeeze the 2 "ears" in far enough to pull the cap out.

I hooked up a small grinder and had to remove a significant amount of material to make it so that it just fit and could be removed.

I'm guessing that the Ethanol mixed into the fuel has probably caused the rubber/plastic to swell up some. Has anyone else encountered this problem??

Well, I'm no expert on Ethanol, but I do know that both of you live in areas controlled by the EPA's strict emissions laws, and just in the past few weeks is when they switched the gas from the lighter, 9.0 rvp gas to the summer grade, heavier, 7.8 rvp gas. If I get a chance I'll look at the lab spec's and see what's different in the gas between the two grades.

Ok, well, I looked at the lab spec sheets and I now think I'm barking up the wrong tree. Not much difference betwen 7.8 and 9.0 rvp gasoline.

Notable differences:
Specification normal 9.0 summer 7.8
Aromatics 37% 32%
Benzene .65% .70%
Gum (mg/l) 2mg <.5mg
Olefins 13.7% 14.3%
Sulfur (ppm) 36ppm 48ppm

The spec's I'm looking at are for conventional gasoline, not reformulated. Either of you guys still in a RFG area? I don't know as though anyone is using MTBE anymore, but if you are, that's your problem. MTBE plays havoc on plastics and conventional rubber. Eats the valve seals on the ship, and hauling gasoline is what we do! Certainly not something that Ducati could have thought of 20 years ago...

But I thought MTBE was a half-assed fix for poor air quality during the winter, not summer? I believe that either MTBE or Ethanol has to be labelled on the pump...

I remember a similar problem disussed either here or in the mailing list longer time ago. The gas cap wouldn`t come off due to underpressure building up in the tank for some reason. Let`s see if I can find it.

G.

Just passed 27,000 miles on the odo this weekend on a run up to Santa Barbara from my home in San Diego area, and had difficulty removing the gas cap, as some of you described. This is not the first time, although until this spring I've not had the problem at all.

At first I suspected misalignment of the plastic bit with the actual cap, but on closer inspection, the plastic part does appear to have gotten slightly larger.

I'm not much of a wrench, but perhaps a gentle sanding of the plastic surface without changing the contour would solve the problem, as suggested by our man jcslocum.

My only question is, should the surface be finished back to smooth after removing the material? For some reason, I worry that rough surface may accumulate nasty stuff, need to seal to somat or some such other mysterious thing. :confused:

The seal is made by an o-ring up higher and not by the plastic thing. I just filed it till it fit and went riding.

I plan to find something to seal the tank and take the cap off this weekend and leave it in the sun to heat up and dry out. Maybe that will help shrink it back to it's original size.

I'll let you know how I make out.