aftermarket gascap problems - Ducati.ms - The Ultimate Ducati Forum
 
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post #1 of 6 (permalink) Old Oct 23rd, 2007, 9:34 am Thread Starter
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Thumbs down aftermarket gascap problems

I have recently pick up a 98 916 and love everything about the ride except the leaky gascap! The previous owner had put a vortex assembly on and it leaks out the top! Ouch...this hurts the paint big time.

The first time i noticed this I was on my first long trip and had to fix it in a parking garage. I noticed that with the tank bag on the cap would create pressure and would push fuel and vapors up the cap. When I took off the assembly I noticed that there was gas collecting under the cap with no where to go. After cleaning this up I just put everything back together an cut a hole in the base of the tank bag. This got me home.

After looking at the parts diagrams for the tank and pump I decided to dig into this a little further.

The tank has all the vent holes on the top and bottom sealed off. the hose going to the charcoal canister was connected to a closed off hole! What is going on here? My thinking now is to unplug one of the holes on top and bottom of the tank, install a hose inside the tank to connect the two then have this going to the cannister. This still doesn't work. fuel still leaks out the top.

I have unplugged both of the bottom vent holes and installed a T for the vent hose. I have since removed the charcoal canister and plugged the holes in the intakes. both of these are connected by hoses inside the tank up to the top holes. I have only unplugged the small hole. The one at about the 7 o'clock position. there is another at the 6 o'clock position that is bigger and looks like it is for the stock cap. should I open this one up as well?

I have tried different gaskets but am still not satisfied. Has anyone else experienced this? What am I doing wrong?
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post #2 of 6 (permalink) Old Oct 23rd, 2007, 10:01 am
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I'm not being sarcastic when I say your post is spinning my head around and I don't know what you're talking about.

However I just wanted to chime in...my buddy and I have LightTech gas caps. My tech installed mine using the stock gasket as well as the one provided by LightTech. My buddy installed only the LightTech one. My buddy's cap leaks, mine doesn't.

I have no idea if that helps at all but want to throw it out there...good luck.

Quote:
Originally Posted by korky37
I have recently pick up a 98 916 and love everything about the ride except the leaky gascap! The previous owner had put a vortex assembly on and it leaks out the top! Ouch...this hurts the paint big time.

The first time i noticed this I was on my first long trip and had to fix it in a parking garage. I noticed that with the tank bag on the cap would create pressure and would push fuel and vapors up the cap. When I took off the assembly I noticed that there was gas collecting under the cap with no where to go. After cleaning this up I just put everything back together an cut a hole in the base of the tank bag. This got me home.

After looking at the parts diagrams for the tank and pump I decided to dig into this a little further.

The tank has all the vent holes on the top and bottom sealed off. the hose going to the charcoal canister was connected to a closed off hole! What is going on here? My thinking now is to unplug one of the holes on top and bottom of the tank, install a hose inside the tank to connect the two then have this going to the cannister. This still doesn't work. fuel still leaks out the top.

I have unplugged both of the bottom vent holes and installed a T for the vent hose. I have since removed the charcoal canister and plugged the holes in the intakes. both of these are connected by hoses inside the tank up to the top holes. I have only unplugged the small hole. The one at about the 7 o'clock position. there is another at the 6 o'clock position that is bigger and looks like it is for the stock cap. should I open this one up as well?

I have tried different gaskets but am still not satisfied. Has anyone else experienced this? What am I doing wrong?

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post #3 of 6 (permalink) Old Oct 23rd, 2007, 10:25 am Thread Starter
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my head is spinning as well!

Thanks for the reply. I now have another option with the stock gasket and the one supplied by Vortex.

I have found a thicker gasket at the local Farm store. we will see how it goes.
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post #4 of 6 (permalink) Old Oct 23rd, 2007, 12:10 pm
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There are 2 hoses, one for the canister which collects fumes and one which is a over-fill so if you spill it just goes to the street. You can take both hoses and T them together so they'll spill on the street. You don't need that bloody canister, thats just for DOT/EPA regulations.

Getting a new seal for the fuel cap, may help... but I doubt it, you could have another problem which I've encountered before when the rubber over-fill piece gets worn out and cracks. I'd take the cap assembly off and check underneath it. You should have a piece of rubber sticking up from right next to the fill hole. That can crack and eventually break off causing spilled fuel to hang out there, where its not needed.
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post #5 of 6 (permalink) Old Oct 23rd, 2007, 4:59 pm
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I think I understand what you are getting at... the previous owner/installer plugged up both the vent and the overflow hoses (which is what the two "holes" are for), causing overpressure in the tank as the fuel warmed up and expanded.

The vent hose should go to a baffle inside the tank, probably on the underside of the inner part of the cap. The overflow hose should connect to the inside of the fuel cap, so when you overfill, it runs out of a hose and into the evap canister or the ground (USA vs. EU). As I understand, you have already removed the charcoal/evap. canister and plugged the hoses that formally connected the canister to the intake manifolds (to burn off fuel vapors).

It sounds like you already made the correct fix. You can connect the vent and overflow (outside of the tank) with a "T" fitting and run a single line to below head-pipe level. Just make sure the lines inside the tank are connected to their respective receptacles and you should be fine.

-MATT
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post #6 of 6 (permalink) Old Oct 23rd, 2007, 9:10 pm Thread Starter
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Thanks everyone for your responses.

This is what I have found.

The rubber piece that should be under the cap assembly for the overflow is missing and plugged just as tye1138 has stated.

There is a weep hole in the cap assembly for the heat/expansion of the fuel and it is located exactly above where this rubber piece should be. It all makes sense now. Fuel is sloshing up through the spout and falling down the weep hole and collecting under the cap assembly on top of the tank.

My next trick is going to be finding a rubber piece and attaching it to the tank. Any suggestions?

tye1138, I look forward to receiving the corbin seat!

Again thanks everyone.
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