Suddenly motor stops?

[mcold]

Hi.

My motor sometimes stops, especially for longer motorway traffic. I can run 15-20km and then the engine goes out? Then I can wait 2 minutes and then it starts fine again. But if I put the tank chicken on reserve, it doesn't happen and it runs fine. Does anyone know what I can do about it? (It is apparently a known problem with the GS500 ...)

[mr72]

It's not a "known problem", or really common. It indicates either you have a vacuum leak so there's insufficient vacuum to the petcock to keep it on, or the petcock is failing and you should replace it.

While everyone likes to blame the petcock, I think it's far more likely you have a vacuum leak so I'd check that first especially considering it's free or nearly free to fix and vacuum leaks will cause numerous other issues. BTW don't spray carb cleaner on anything! My method of "checking" for vacuum leaks is actually to just replace anything that could cause the leak, like $10 worth of o-rings and hoses.

[Watcher]

Runs fine on "res" but not on "on"?

That's an odd one.  Definitely not a "known issue".


I think mr72 is incorrect, though, as res also runs on vacuum.
I think the screen inside the tank is clogged.  There's, for lack of a better word, a straw sticking up into the fuel tank that serves to provide the reserve function.  When fuel level is below the straw "on" no longer functions, and the "reserve" is simply an inlet lower in the tank.
I think that "straw" is clogged.

[herennow]

Just to make sure, your tank is full? The GS has a large "unused" capacity in the tank due to its design and you can be out of gas, thinking it should still have enough.