bike dies after running 40-50 miles

[Anonymous]

Hello, looking for some help from the experts on here.

Bike is a 1980 GS1000GL got it about 1 month ago, has run fine around town and idles smoothly. So finally last weekend time for the longer ride, well it stopped after about 50 miles, symptoms really felt like it was running out of gas. Since tank was near empty, figured that was it. Coasted into a gas station, filled up (hmm only took 2.5 gallons and it's a 3.5 tank). Overall the stop was about 15 minutes, it started right up and then ran fine 20 miles to home.

So today, bike did the same thing ran perfect for about 50 miles. Started dying, first symptoms were no reaction to more throttle. Coasted to a stop. So this time I just repeated what I did before, removed gas cap, sat for 15 minutes. Started up fine and got me the 10 miles home.

Idea's? It sure seems like a fuel/vacuum issue to me, but what and where should I be looking?

thanks much
mike

[Anonymous]

Sounds like it may by the vent in the gas cap. Vacuum builds up after a while, which stops fuel flow. Openning the cap allows air in, so it starts up again. Clean out the cap to see if that solves the problem.

[Anonymous]

Could be a bad line or connection for the vacuum line that controls the flow of fuel thru the petcock. If that was it , turning to the "prime" position would restore the flow (don't forget to turn it back to "on" when you shut down). If switching to "prime" (not reserve") doesn't solve the problem then that ain't it.
Another possiblity is you've got crud built up in your gas cap & it's not venting, causing a vaccuum in the tank and again no fuel flow. Did you hear a 'whoosing" sound when you removed the cap?
Could also be something heat related with your ignition--it fails when it heats up. From what you describe my 1st guess is that it's a fuel delivery problem. When it happens you need to pull one of the plugs and ground it on the engine--with its wire attached, of course. Hit the starter and see if you've got a healthy spark--be careful not to get zapped!
Other possiblities:Crud in the tank that's plugging the screen that's attached to the petcock. A dirty inline fuel filter if someone installed one.
I'm FAR from an expert but hope something here helps ya out. Good Luck!

ED

[Anonymous]

Thanks for tips, yea my first guess is/was gas cap venting, but a quick look at this cap and I can't even see how the venting works? Looks like a solid rubber seal all around the rim? I'll disassembly it tomorrow in any case. Didn't hear any sucking sounds on removal and was watching for it the 2nd time.

This bike has what some call the no petcock, petcock, takes a small flathead screwdriver to turn to prime. but thanks on my next test ride, I'll make sure I'm ready to both move it to prime and also check for a spark. Since it appears the problem goes away quickly, it if turns out to be more then just a gas cap vent issue, might be a real bugger to find.

[focus frenzy]

check for any kinks in the fuel line and also make sure the vacume line to the petcock is in good shape and is not kinked.

[Anonymous]

Thanks for tips, yea my first guess is/was gas cap venting, but a quick look at this cap and I can't even see how the venting works? Looks like a solid rubber seal all around the rim? I'll disassembly it tomorrow in any case. Didn't hear any sucking sounds on removal and was watching for it the 2nd time.

This bike has what some call the no petcock, petcock, takes a small flathead screwdriver to turn to prime. but thanks on my next test ride, I'll make sure I'm ready to both move it to prime and also check for a spark. Since it appears the problem goes away quickly, it if turns out to be more then just a gas cap vent issue, might be a real bugger to find.

The simple test for gas tank vacuum is to create the condition, then just open the cap, put it back, and carry on. No need to clean out the cap if this test doesn't show any change.

[Anonymous]

I had a similar problem last year. But my distance was much shorter before the bike died. It was more like ten miles. The problem, for me, turned out to be a defective fuel filter. I rode it home. But not after it died on me in the rain and I stepped off the bike into a ditch. Yeah, I laid it down. Took me something like forty five minutes to get the thing back on its wheels. But I digress.... The next day I took the fuel filter off and it had fuel in it still. It wasn't flowing out as it should have been. So, I blew it's contents into a glass and voila I got mostly water. The paper element had absorbed the water and wasn't allowing the fuel to flow. No more el cheapo fuel filters only the metal type for me from then on. I hope that this is the easy fix for you.