Triumphrat

TBABill · 11-16-2009, 10:48 AM

I have read the multiple reviews of people with engines cutting off while riding, but none seem identical to my problem so I am seeking help of fellow riders.

My 08 America with 9000 miles has been cutting off on me on the way to work each day. It warms for a few minutes, then I ride with the choke still partially engaged for a mile or so till the engine feels smooth. I push the choke in and ride for up to 15 miles before having problems, but sometimes sooner. Never happens at other times of day besides early morning (6am EST). The engine sputters like it is running out of gas and then quits. I have switched to reserve while happening - no help. I let it sit for 1 minute or less and fire it right back up and ride on with no problems. This is not an immediate cutoff like you would have with a kickstand, electrical or switch problem, but what seems like a fuel or vacuum issue.

Are there any valves in the airbox that could be my problem? The vent line is not pinched from the tank to the air box. I have pulled it and I can blow through the line fairly easily. I have not been in a situation where I can loosen the gas cap while it happens because I am normally trying to get off the road quickly to keep from getting hit from behind. Tomorrow I will try to ride all the way to work with the gas cap loose and see if I notice any change.

Beyond the gas cap loosening, where do I go next? All vacuum caps are good (replaced one that was cracked, but not the problem) and AI was removed many months ago with no problems. Vacuum lines appear solid and are as far onto the fittings as possible.

What type of connection does the vent line have at the air box? I have never pulled it from the air box. I doubt it is a fuel in the airbox issue because it starts right back up and runs normally.

Any and all ideas welcome!! I live an hour from the nearest dealer so I will fix it myself if I can.

Overkill0084 · 11-16-2009, 05:30 PM

First thing I would check- ensure that the fuel tank vent is clear and not kinked. If it's blocked, you can get a vacuum in the tank that will slow/stop fuel flow. If/when it acts up next time, check the gas cap. Loosen it up and if you hear an inrush of air, then the vent tube is likely the problem. It's the one that looks like an unneeded vacuum line under your tank.
From there- Check every electical connection for security. I know, it's probably not electrical, but you want to rule it out nonetheless. A loose connection somewhere can drive you crazy.
Disclaimer: I claim no Guru status. Just offering starting points. Good Luck.

TBABill · 11-17-2009, 12:18 PM

Just an update. I disconnected the tank vent hose and ran a new one (about 5' of 1/4" rubber fuel line) right next to the existing one. I drove to work this morning and the bike was flawless. I had better acceleration than I have had in quite some time and no hint of trying to cutoff like it had been.

As other posts have stated there is a tipover valve in line with the fuel vent hose. That valve gets stuck and does not operate correctly, starving the fuel tank of air to replace used fuel and creating a vacuum so fuel is, in effect, cutoff. Apparently that is a high failure item according to the dealer and a $5 fix to just bypass it with a new hose.

Runs great now!

Nang · 11-18-2009, 05:10 AM

I assume all 865/790 twins have the same typeof gas cap. Mine has a one valve in the centre of the cap. Take yours off and there should be an obvious plastic valve on the inside centre. try and suck air through it. If you can't thats the air vent blocked and you should be able free it upby rapidly shaking the cap/sucking and blowing. Running a hose like you have done may have solved your problem but you now probably don't have a roll over cut off. Note that the vent line is for coping with expanding fuel overflow.