Cutting out on freeway: clogged gas cap vent or frame petcock?

[Zwerski]

This morning, I went out for a ride to test out my new gear, and had some problems on the freeway several times.

I think it's related to when I fueled up and spilled some gas onto the tank cap ring on the outside of the tank, and also around the filler tube inside the tank. First time since I've had the bike (2 years) that fuel has spilled like this.

A few minutes later, after about 2 miles on the freeway and full speed, I got fuel starvation symptoms - sputtering and loss of power. Pulled off to the shoulder and switched the frame petcock to RES (thought it was PRI) and there was no immediate change in engine condition, and engine stalled. Opened tank cap, closed it back up, and had to start bike with choke, but it started after two tries, and I took off to continue my trip with petcock on RES, running the bike on the freeway for a mile, then on some back roads at lower RPM and speeds.

Later, during a rest, I switched petcock back to ON and set out on the back roads again. Then, I again needed to travel on the freeway. Again after a couple miles, the same symptom as before started again. This time, I switched to PRI, bike started right up, and I kept on my way the rest of the way, about 5 miles on freeway. to my next stop.

At next destination, switched petcock to ON and ran on freeway for about two miles, then city streets for a few and no problems. Rode the bike yesterday on expressways ans city streets with no problems.

97 E / 11,XXX miles / bone stock / non-CA model

Thanks for looking.

[jestercinti]

Was it windy?  Carb vent hose kinked?

Had bizarre things like this happen to me too. It turned out that my carb vent hose was in the wind and causing pressure problems. Positive pressure I think.

Search for "crosswind engine stumble"

[Zwerski]

After NO changes on the bike, went and ran it for 20 miles at highway speed yesterday with petcock at ON position with no issues. Was not particularly windy on wither day. Strange.

[weedahoe]

Mine used to do this. I thought it was the frame petcock because when I put it in PRI it would run fine. I bought 1 new 09 petcock and it still does it so know I just ride with it in the PRI position

[jestercinti]

I'll add another possibility (albeit a far off one).

When I had my GS450 (somewhat similar to the 500), it used to do the same thing.  Intermittent stumble, only on the highway.  Lived with it for a year before the CDI Ignition module went bad...it was slowly failing which was causing the stumble.

So...Ignition might be it too, but I'd focus on fuel starvation first.

[sytsmadad]

You said it started right after you fueled up right. If you do not have an inline fueld filter you may have gotten some crap in the tank from the lip around the tank lid. This could have caused a partial obstruction in the fuel line. Take the lines off, blow them out with a compressor and put them back on with a fuel filter.

[cbrfxr67]

I had a problem like this and just bought a new one of ebay for around 40.  Haven't had that issue since,...

[Zwerski]

When I had my GS450 (somewhat similar to the 500), it used to do the same thing.  Intermittent stumble, only on the highway.  Lived with it for a year before the CDI Ignition module went bad...it was slowly failing which was causing the stumble.

Oh, man. Don't say that!

I had a problem like this and just bought a new one of ebay for around 40.  Haven't had that issue since,...

Which? Petcock or CDI?