GS keeps dying on the road :(

[dwoloz]

1993 federal model

The bike has died on me several times, just sputters out like its not getting fuel.

I thought for sure it was the fuel petcock so I replaced that with a brand new one. Went on a ride yesterday, died on me twice at highways speeds (6K rpm). It then refuses to start for about 2 minutes but eventually turns over while turning the throttle. Maybe its starved for fuel, maybe its flooding with fuel? Maybe the petcock isnt getting vacuum?

Any tips on what I should check next? I'm planning a 200 mile ride next month and I'd like a bike that doesn't just suddenly die on the highway 

[LOUiE]

re-check your fuel lines... mine were crossed up when I got my bike... sounds like the same situation as I had.

Could be possible that your ON line is accidentally connected to you RES line or really any other combination.
There are a few threads going on about this.

Here's a quote from another post...

Make sure all lines are hooked up properly:

http://img.photobucket.com/albums/v443/jcp8832/01-02fuelcock.jpg

http://img.photobucket.com/albums/v443/jcp8832/04-06fuelcock.jpg

http://img.photobucket.com/albums/v443/jcp8832/89-00fuelcock.jpg

MIGHT also be a good idea to check if the fuel switch under the tank is FULLY on ON.  This one's just a thought.

[lilbill]

+1 to LOUIE and:
Most of the ideas in you OP are where you should start.  First just make sure that you have gas in the tank, flip it to prime when it starts to see if that remedies it, check the vacuum to the petcock if the prime thing helps.

Also check your hose routing:
http://www.bbburma.net/FuelHoseRouting.htm

and the float heights:
http://www.bbburma.net/FloatHeight.htm

The carbs may also need a cleaning could have bits of rust/dirt in the jets...check the inside of the tank with a flashlight for rust and try draining the bowls to see if any crap comes out.

Hope that's a good start

Keep us posted

[dwoloz]

I was rather careful with the routing, I'm fairly sure I did it right, used this as a guide

[Ry_Guy]

what do your plugs look like?

[theGrinch]

Although it's normally a problem for continuous driving in high revs, your description matches it.
Try the petcock on PRI.

According to what happens there are several possibilities, but you've got one starting point. I'll try to get that page translated later, maybe google translator helps in the meantime: http://www.gs-500.info/index.php?title=GS_geht_nach_Vollgasfahrt_aus

As I said, the problem described on the page normally occurs when you go flat out for some time - your description (spluttering as if no petrol, takes some time until it restarts) does match on the other hand.

[beRto]

Are you sure there's enough fuel in the tank? I suggest filling the tank before proceeding with further testing.

[dwoloz]

Haven't pulled the plugs yet, will do that

I topped off the tank before this trip, there is fuel in there

theGrinch: My first thought was the petcock and thats why I replaced it with a brand new model. I think what you're describing is a faulty petcock with a bad vacuum diaphragm, my new one obviously wouldnt have this problem. But if its still not getting vacuum from the carb, that could be an issue. I dont know how likely that is though

[DoD#i]

Check the tank vent. If "2 minutes" becomes "a few seconds" when you pop the gas cap while sitting beside the road, that's a likely suspect.
http://gstwins.com/gsboard/index.php?topic=41061.0

As for bad vacuum, despite all the hand-wringing about the prime passages being smaller, they will normally flow plenty of fuel to verify if the problem shows up when you run the bike in prime, or not.

[beRto]

1993 federal model

What is a "federal" model? Does this mean it is restricted somehow?

[DoD#i]

...not California. A 49-stater. Hasn't got all the ha-ha-ifornia emissions control junque on it.

[the mole]

You've replaced the petcock, but what about the old vacuum hose? May have a crack/pinhole.

[theGrinch]

Just translated it, might have some helpful points for you: http://www.gs-500.info/index.php?title=Dies_whilst_riding_at_full_throttle

(If anybody has any better words for the technical stuff (i.e. float needle valve), please let me now.)

[the mole]

The Grinch's last link should go in the Wiki, its a great aid for troubleshooting the fuel system. Thanks G!

[theGrinch]

The Grinch's last link should go in the Wiki, its a great aid for troubleshooting the fuel system. Thanks G!

I just did the translation, the knowledge is from AmigaHarry
We have a cooperation between the US wiki and the German one, feel free to link it.

[dwoloz]

Thanks for that translation!

This problem has happened before in PRI (this was prior to the petcock replacement).


This caught my eye:

If you park the bike, you should swith the petcock back to ON, otherwise the carbs get flooded if the float needle valve is broken (not a rare fault).

When I first bought the bike I didn't realize the valve was in prime (from the previous owner) and left it that way overnight. The garage smelled of gas the next day. Switched to valve to on and the smell was gone. So I suppose this means I have a bad float needle valve?

[theGrinch]

Possibly - which in turn might explain your starvation problem!
If you're brave you can see if you can reproduce the smell by leaving it on PRI overnight again - but you wanna make sure the airbox drain works, otherwise you flood your engine and ultimately the oil with petrol -> not a good idea.

If you have excluded everything else, a carb clean and possible needle replacement is in order. If you don't fancy doing it yourself, somebody on here was offering it. (was it the buddha?)

[dwoloz]

So, here is what I have checked so far:

Fuel routing is correct
All lines secure, no leaks

Air filter was just replaced

I shined a flashlight in the tank, looks very clean, no rust. Filter looks fine, can't see anything really on it.

Pulled the fuel filler assembly, took it apart, looked pretty damn clean already, someone probably did it before. Cleaned it up anyway. Put it back together after much frustration, probably screwed it up more than what I started with, doesn't work the same anymore, bah. Vent is definitely clear though

Checked the float heights using this method http://www.bbburma.net/FloatHeight.htm and the non driveside carb is fine, the driveside carb's level is about .5in above the gasket line. Don't know if this is enough to screw with things but its definitely off.

Pulled a plug, doesn't look bad at all. Heres a picture:


Wanted to check vacuum on the line leading to the petcock but theres no easy way to get at it without taking off the tank and I was far too lazy to do that.

I need the bike to commute on for school that starts the 25th so I really just wanted to have a shop look at it and fix it but nope, thats not even an option, all the shops in town are booked solid for the next 2 weeks.

[bombadillo]

...not California. A 49-stater. Hasn't got all the ha-ha-ifornia emissions control junque on it.

Ha, I'm in PRK (Peoples Republik of Kalifornia) and I don't have any of that junque on it either!!!!!!

[galahs]

Check the vent hose from the t connector for blockages