Yesterday on the way to work Trey died on the freeway and I assumed it was out of gas becuase I put it on reserve and all was good,filled it up and made it to work.On the way home with a full tank it did it again,60mph,80+ degrees it started to act like it was running out of gas and just died.I coasted off the freeway and turned it to reserve and nothing than I tried prime and still wouldn't start.I was getting to push it off the freeway when I decided to remove my tankbag and open the fuel cap,after closing it I tried to start it again and it started and ran fine the rest of the way home.Has anybody ever had a tankbag block the fuel vent??,I use this bag on my Vstrom and it has what looks like the same gas cap as the GS!!.or was it a case of a full tank and a hot day??
Vapor lock



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Check the gas tank vent line maybe its pinched?

I thought it vented thru the cap ??


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#5324

It does vent through the cap into the drain area around the cap. Normally there is space around the cap for air and hence the need for the drain hose as water gets around there when it rains.

Probably a combination of things:
1. The vent hole in the cap might be clogged: corrosion, a bug, speck of dirt
2. Drain hose could be blocked or pinched
3. Tank bag could be making a good seal over the gas cap.

If tank bag removed and bike runs OK then that is blocking air, but still need to clear out alternate path for air (drain hose)
If there is a hiss when opening the gas cap, then the gas cap vent is clogged. If that is it, it makes sense it happened sooner with a full tank: less air in there to expand so vacuum developed quicker. Also possible that when riding the highway, the air flow cooled down the tank and created more vacuum inside the tank.

Still need to figure out what is blocked. The fact that it ran again after letting air back into the tank indicates everything else is OK - just some vacuum is developing as gas goes out and air isn't getting back in.

You can try with the gas cap not fully closed. Unlock it but leave in the down position so  it is slightly opened. That will let air in and should create extra gap under the tank bag for air.

Another thing to try is run without the tank bag.

Whatever eliminates the problem helps identify the air blockage so it can be fixed. Or just be sure the tank drain is working (pour water around the filler hole and see if it drains out) and check the gas cap vent hole.

When I first got my tank bag I used to put a clear piece of thin vinyl on the tank first. Imagine cling wrap on the tank. All air sealed, right? Never had a problem.

I suspect, if your bag is sealing the air and causing a vapor lock your drain hose is clogged. Start with that first.

Michael

My tank bag used to do the same as OP's.
Removed and cleaned the fuel cap and it worked ok for a while.
Found out if i push the tank bag forward enough that i can see the edge of the fuel cap it doesnt block the cap vents, and no, the bag doesnt get in the way of the bars either!

Confused and scared the hell out of me when it first happened - full tank, recent new battery & alternator, 100ish miles from home, and overtaking a lorry at 80mph 

Not sure if Adidas ever had/corrected the vacuum leak problem. Check your carb drain hose, and route it so that it's not in direct contact with wind at high speed. Route it behind the battery box or the engine if possible. If it happens again, flick the fuel selector to 'prime' for a minute. Happens only at high speeds or extreme winds.

Quote from: Dizzledan on August 16, 2012, 04:03:48 PM
Not sure if Adidas ever had/corrected the vacuum leak problem. Check your carb drain hose, and route it so that it's not in direct contact with wind at high speed. Route it behind the battery box or the engine if possible. If it happens again, flick the fuel selector to 'prime' for a minute. Happens only at high speeds or extreme winds.

#5325

Never had vacuum leak problem on Trey. Only problem was a bad spark plug. Probably pinched drain hose or dirty fuel cap vent. We did swap things all over the place last week. Easy fro something to be dirty or a pinched drain hose.

I took the cap off of Trey's blue tank and put it on the purple tank,could I have done something wrong ??


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Quote from: NortwestRider on August 16, 2012, 05:57:24 PM
I took the cap off of Trey's blue tank and put it on the purple tank,could I have done something wrong ??


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Nope. Other than maybe a fleck of dirt clogged the vent hole - not completely, but just enough to cause a momentary problem with high fuel demand and our hot weather (i.e. and tank cooling down due to the wind after getting hot sitting parked for a while).
You can stop over if you want and we can look at things.

Got back from our Canadian trip and spent alittle time with Trey and did some checking.I took off the cap and checked the vent,wow that vent hole is big!!.I put a screw driver wayyyyy down it and found no blockage.Checked all the vent lines and they looked good also.So I don't know what else to check!!,my wife rode it around today with no problems.I will ride it to work latter this week WITHOUT the tank bag and see if that was the problem.


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You're talking about the drain hole.

The vent holes in the cap we speak of are usually something like  you see here:

I say not the tank bags fault.

I ride with my tank bag on 90% of the time and have never seen this issue. Makes me want to take of my cap and clean it though. . . .

Well tomorrow night I will pull off the cap again and check it ..


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Posted once in the other thread, but it needs to be here too, i think:
Ben2Go's writeup with pictures from the FAQ on tank vent cleaning:

http://gstwins.com/gsboard/index.php?topic=41061.0

So today I rode the 500 to work for the first time since this happend ( both my other bikes are down )same route,same time of day and WITHOUT the tank bag.The temps were 15 degrees cooler and I had no problems !!.I really think the problem was the tank bag making a good seal around the cap/vent,I can't prove it but it ran great without the bag.


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What type of tank bag is it?

I rode with this one for 4 years never had a problem.


Although, I do occasionally have this on Flick when I'm on the 417 @ 70mph+ for an hour in 90 degree weather. I switch down to reserve and back no issues afterward. This is without the tankbag.
Mary

I have a basic bilt ( cycle gear ) magnetic bag.I use it everyday on my Vstrom BUT the V's tank is rounder so it doesn't sit flat like it does on the GS.If I was going to use it on the GS i would make a bracket that bolts to the gas cap ring to keep the bag up!.


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