Out of Gas, but tank's half full

[sebring38]

82 GS850. When I am pulling very hard for a few minutes at high speeds around 85-95mps as when passing someone or going up a slight grade, after returning to a slower speed the bike quits. Won't start. I have a clear in line gas filter, so I can see that there is no gas in the line. After a few minutes (3-5) of sitting, and with the petcock set so that the gas will gravity flow, the gas slowly begins to flow to the filter and to the carbs. A little choke and it starts right up and runs as usual. I have noticed this on several occasions when the tank was half full or less than that. Any thoughts on this appreciated.

[lord1234]

you might have a chunk of rust particles that has accumulated...that is able to be sucked into the petcock intake. This gunks up the entire petcock...then when the bike is off it takes it some time to "release"...then you revacuum it and so on and so forth...consider giving your tank a kreeming or por15ing...

[Mysuzyq]

The consensus here seems to be that these in-line filters cause a lot of problems, similar to your description. Try bypassing the filter, or running with a new/cleaned one installed. If the tank is in bad shape inside, you might want to address that issue before running without the filter! Another thing to check would be the gas tank cap....there should be venting to prevent a vacuum condition inside the tank...I took the cap apart as far as it I could, and cleaned out whatever 'gunk' I could see (my problem turned out to be not fuel starvation, but a dying battery). Also check to see if the prob occours with the petcock in the 'res/prime' position (make sure to take it off prime after the 'test' )....to rule out a bad petcock.

Tony.

[MekaniX]

take the petcock off and clean it, look for a busted diaphram or something ubstructing fuel flow ,,,

you said that it does fill up on prime , so that's why i think the diaphram is either not moving properly or is busted. Or it could be just a cloged filter .

[tconroy]

82 GS850. When I am pulling very hard for a few minutes at high speeds around 85-95mps as when passing someone or going up a slight grade, after returning to a slower speed the bike quits. Won't start. I have a clear in line gas filter, so I can see that there is no gas in the line. After a few minutes (3-5) of sitting, and with the petcock set so that the gas will gravity flow, the gas slowly begins to flow to the filter and to the carbs. A little choke and it starts right up and runs as usual. I have noticed this on several occasions when the tank was half full or less than that. Any thoughts on this appreciated.

Do you have a paper filter or an inline motorcycle filter.the ones with the brass inside? It makes a big difference.The paper filter will not let the petcock "catch up" with the carbs demand on fuel consumption, thus starving the fuel supply to the carbs.Get a metal filter of get rid of it completly.I run an inline filter and have no problems at all.Make sure the filter is below the petcock running vertical not horizontal also since the fuel system is gravity feed.

[Ghostgs1]

Check the vent on the gas cap, I've heard of them causing symptoms like yours. Ray

[brveagle]

Check the vent on the gas cap, I've heard of them causing symptoms like yours. Ray

i was going to say the same thing..

When our bikes are running, the tanks become pressureized to "force" the fuel out of the tank, via petcock. If you lose that pressure, then the fuel won't feed right.

[sebring38]

Sounds like a good thing to try. Will first remove the paper inline filter and try it. This leads to next question: I put the filter in there because of rust in the tank. What is the best way to get the rust out of the tank, and then is there a product that can coat the inside of the tank to prevent more rust?
thanks for all the replies. Great ideas and I intend to try them all this Saturday.
Keith sebring38

[drcoopster]

When our bikes are running, the tanks become pressureized to "force" the fuel out of the tank, via petcock. If you lose that pressure, then the fuel won't feed right.

Doesn't quite work that way. The petcock is merely a vacuum-actuated valve. When the engine is running, vacuum is applied to the valve and it opens, allowing fuel to flow to the carbs.

The vent on the fuel cap is to allow air into the tank to replace the gas that has been flowing (only by gravity) out of the tank.

-Ian