Ok so I have a 12 mile commute, and about 6 miles in there is a 2 mile uphill highway stretch I usually take at around 60-70 mph.
The issue has happened twice where I will get about half way up the hill and the bike starts acting like it is out of fuel. First time this happened I switched to reserve and it got better (about 120 miles in on that tank, usually get about 150-170miles per tank). Just yesterday I was riding to work and it ran out of fuel and quit, reserve didnt work and I had to set it to prime and It kicked over and ran fine. I had only driven 26 miles on that tank of fuel.

Both times I switched back to "ON" once I got to the top of the hill about a mile away and it didn't happen again the rest of the way to work.

I was thinking its the petcock, but it has only happened on that hill and it had been weeks since it had last happened so I attributed it to random crud in the tank.
Has anyone had a similar experience? I have never had Audrey let me down before and its kind of worrisome.

just a thought if you are low on gas and going up a hill if it is steep hill maybe what little gas you have is at the back of the tank and cant get to the fuel line??? just a thought

What gear and what rpm is this happening at? Sounds a lot like the famous high speed starvation problem on this bike. I've run into it while riding 75mph on the interstate with a headwind and hills. It starts out feeling like the engine can't pull enough fuel and then you unpredictably start bucking while going that speed.

Shifting down a gear didn't help.
Some say its a fuel vapor lock issue and recommend opening the fuel tank cap to allow flow.
Others have swapped to a Honda dirtbike petcock
Some have tried modifying the petcock vacuum
I saw one mention it has to do with the carb breather hose?

I wish I had an answer but this is one of the problems that I never found a conclusive answer to. Sure some here will say its easily fixable or that it never happens,  but its damn frightening to be going interstate speeds and then the bike becomes very unpredictable.

My opinion is the GS simply wasn't made to go that fast and the carbs aren't designed to function 100% reliably under those conditions. I'll do up to 65mph all day long on the GS, but once I need to go faster it just seems like the bike is in foreign territory.

I have an '04, and it does 75-80 for 6.5 hours every weekend past 4 weeks = aprox. 1700 miles... without missing a beat
... you shouldn't have fueling issues at any speed without something wrong. 

Dinky, most fuel starvation issues like this are simple fixes - the hard part is figuring out what is causing it, because they all have such similar symptoms.  When someone just says their bike keeps running outta fuel at speed (or similar description) - we tend to throw on the table all the possible causes of fuel starvation that aren't inside the carbs first - because they are the simplest to fix.  They seem elusive, but they aren't hard to diagnose if you are directly checking for each one.

Because it happened sooner with a full tank for the OP, I am pointing toward your tank vent.  But switching to prime and it being fine thereafter, makes me point toward an issue in the petcock. 

To diagnose a vapour locked tank (from a tank bag, or clogged tank vent or similar), simply open the tank when the problem occurs. If air whooshes in when you open it (you can hear it), then that's the problem.

The other possibility I mentioned with the frame petcock vacuum - would require inspecting the vacuum line, and opening the petcock to inspect the diaphragm to diagnose.

- Bboy

When I've experienced the same symptoms, I switched the petcock to prime (on the fly) and the problem goes away.  So, now when I know I'll be riding at sustained speeds over 65, I just flip the petcock to prime and I haven't had a problem.

Quote from: Blairbee on July 30, 2014, 01:37:05 AM
just a thought if you are low on gas and going up a hill if it is steep hill maybe what little gas you have is at the back of the tank and cant get to the fuel line??? just a thought

I originally would have thought this but when it happened on a full tank the second time like I mentioned it made me doubt it was a fuel level issue. Now that I think back a bit I did have a similar situation about a year ago while climbing a mountain pass @6500 ft elevation, not an appreciably steep incline in either of these situations.
In all of these situations I was running about 5000-6000rpm and the air temp was around 60°f



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BBoy,
I will check the tank vent when I get home, the petcock as well. I have had little problems with the bike and regularly take long trips with her so thank you for the assist!

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Quote from: mimikeni on July 30, 2014, 07:56:48 AM
When I've experienced the same symptoms, I switched the petcock to prime (on the fly) and the problem goes away.  So, now when I know I'll be riding at sustained speeds over 65, I just flip the petcock to prime and I haven't had a problem.

If this is your problem too, you need to check the petcock diaphragm for holes, tears. Prime bypasses the circuit with the diaphragm.

I just started encountering a similar situation - although not anywhere near highway speeds.  If I maintain 4-5k rpm and above (so basically any riding) after a few minutes the bike will start to lag and eventually stall.  Flip it to prime and it will fire back up or stay running if I catch it in time.  Started happening this past weekend.

Tried it this evening, it died as expected, so I returned to my garage and removed the frame petcock.  I noticed traces of fuel in the vacuum line...not a lot, but the hose itself had a small layer of fuel forming a "bubble" when I first removed it.  Guessing this is not normal.  Is this most likely a leak in the diaphragm?  It's a '97 500e.

Yep, your petcock diaphragm is compromised.  Time to repair or replace the petcock.  Common topic here, so many replace with a manual, non-vacuum petcock.

Quote from: bombsquad83 on August 15, 2014, 07:14:34 PM
Yep, your petcock diaphragm is compromised.  Time to repair or replace the petcock.  Common topic here, so many replace with a manual, non-vacuum petcock.

just have to remember 2 things.
"Turn the gas on dummy" and post ride "turn the gas off dummy" youll only get caught once lol