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Discussion Starter · #1 ·
Posting for posterity.

Background: I only recently bought my 9 and have not really had a chance to ride her for any length of time that would draw the tank below half way before I would fill it.

Two days ago I went on a nice, long ride. I would guess my tank was about 2/3 full. About 45 minutes into the ride I started to get a stumble/hiccup. I would apply a touch more throttle, or gun it, and the engine would cut out for a split second. It got worse and worse over the next 30 minutes - but never consistent where it was doing it non-stop or anything close to that.

Note: I did add a little less than half a bottle of techron fuel cleaner to the tank of gas in question. And I always use premium gas.

My most likely causes:
  1. bad gas, or water or some other contaminant that only got into the fuel system when the tank was low on fuel.
  2. blocked fuel strainer (filter).
  3. Gas tank is not venting.
After my gas light came on I stopped and filled the tank. The first thing I noticed was a tiny 'whoosh' when I popped the gas cap. I proceeded to fill the tank and left. She stumbled twice in the first thirty seconds, but very infrequently for the remaining 20 minute ride home.

Yesterday I took the gas cap apart and thoroughly cleaned everything. It was pretty gunked up, so hopefully it was just not venting like it should. I also ordered a new fuel strainer for the pump pickup.

I'll report back in a few days if the problem persists or if the new gas and cleaned gas cap vent solved the issue. To be continued...
 

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There is a little teeny piece of metal in the cap that sometimes gets out of place. When that happens the gas tank won't vent properly. Happened to me once several years ago. I had to take the gas cap off numerous times in order to get the bike home. Because it would run for about five minutes, then stall completely. After I fixed that teeny piece of metal, never happened again. And yes, the fuel filters on these go bad about every 10,000 miles or so. Mine has anyway. Owned the bike 16 years, changed the fuel filter three times. Just turned 39,000 miles Sunday.

Since the last filter change, I bought three fuel container nozzles from my local Tractor Supply. These eliminate those funky new EPA nozzles and turn the container into an old fashioned one. They also have a filter in the nozzle. And, I took one of those white medical filters and fitted it into one of my funnels. I keep 10 to 15 gallons of 93 octane in my garage at all times. And I like to fill the bike after every ride. I pour fuel from the container into a half gallon liquor bottle, using both the nozzle and funnel filter. Then pour it into the bike using the funnel filter. So it's filtered three times from the container into the bike. And YES, you should see some of the crap the filters trap.

We'll see just how long this newest fuel filter lasts this time.
 

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Discussion Starter · #3 ·
Thanks. I actually read one of your posts from a while back that mentioned the tiny piece of metal before disassembly of my cap. I was picturing some sort of pin, not the tiniest of tiny pieces of stamped metal, LOL! Regardless, mine looked to be installed correctly but the rubber gasket had a good amount of gunk in/on/under it. Hopefully that was the issue.
 

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And I knew of it because someone, long before me, posted about the exact same issue. Apparently some bikes will run when the cap isn't venting properly. Because there have been pics in the past of collapsed fuel tanks, from the tank attaining a YUGE amount of internal vacuum. I fail to see how that happens myself. As I said, my bike wouldn't run when the cap wasn't venting. When it happened, I at first thought it was another plugged fuel filter. But while pulled over, I removed the fuel cap and reinstalled it, and the bike ran fine, for about five minutes. I was 15 miles from home, had to remove the damn cap at practically every stop light in order to get it home.

I don't know what caused mine to get out of place, and why it hasn't happened again since?

16 years, 39,000 miles. Three fuel filters, four if you count the original. And three clutch cables, if you count the original. I have the fourth one in my Corbin Smuggler. Yes I know how to set the clutch free play. The original, the cable pulled out of the lower barrel. The second and third both frayed at the top by the lever. Does anyone make a "Heavy Duty" clutch cable for these. Or is converting it to a hydraulic clutch the only fix?
 

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Dirtie, what year is your 9? Early models used a vented tank, later models added a vapor collection canister and used an unvented cap. Neither system should allow the tank to build pressure or vacuum, so hopefully you found your problem.

If you look back through the forum, or maybe search for unvented fuel tank cap, there are some pictures of what happens when the cap stops venting or the wrong cap is used. When the tank cools and can't get air in to vent it, the tank collapses catastrophically. o_O
 

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Discussion Starter · #6 ·
Mine is a 2012. My cap is definitely capable of venting as I did the suck test... wait... that may have come out wrong... Anyways, I was able to 'provide vacuum' to one of the ports on the bottom of the cap and feel air coming in via a rubber gasket that has two prongs that insert into holes in the cap itself.

I've read about those tanks collapsing. Ugh. If I read right it seems like nobody had it collapse during use, as the engine would stop getting fuel before that much vacuum occurred, but as the tank cooled overnight the vacuum would continue to build and collapse the tank. I can't imagine going out to the garage in the morning and seeing my tank collapsed... Wow. And then to find out it was due to an aftermarket cap from a total wanker of a vendor... not cool.

Anyways, only short trips so far and all is well. I'm only at 5.2k miles, but I'll replace the fuel strainer in the tank in the next few months.
 
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