So this started over on other forums, but when it got GS specific it died, I think I brought it up here but this is the first time in real depth. I ran out of gas probably about a week ago, and switching to reserve did nothing. I looked into it, and checked again with dad and we are both pretty confident now (he did not believe me ) the hoses are reversed. Problem is this. Today I ran out of gas again. I had been running it on reserve, figuring I run out, switch it to on. Did not work! My dad brought gas by (this was on the freeway, so embarassing ) and took a look inside- granted his experience is not on anything similar to a GS500, but he felt there should have been enough gas in there to be running.

It starts and runs just fine on either setting (can't be a clog in the reserve line then).

That being said. I have to admit when I ran out of gas on the freeway the last thing to cross my mind (darnnit!) was to check the petcock. There is a chance I had for some reason switched it back to on (again, plan was with reversed hoses to switch it to on when I ran out, for actual reserve). I cannot promise it was not. I am going to try and grab a pump siphon at the shop tomorrow or something to run out of gas again soon (and close to home) to confirm. But I wanted to start the troubleshooting as I would really prefer to fix any problems myself (both to save money, and for fun/to learn).

So, if it starts and runs on both settings, and the hoses are reversed but neither appears to be acting as a reserve... what problems could it be?

P.S. Don't want to start another thread for it. What fuel is necessary for the GS500? I think manual said 87 octane, but I know there are different ways of measuring it. I have been using premium just to be safe but its time to find out for real .

Maybe the petcock is broken? I don't know what a GS petcock looks like, but most have a tube that goes up a little higher for the "on" setting (reserve is flush with the bottom of the tank). If the tube breaks off, it wouldn't matter which setting it's on- both will use up all the gas.

And 87 octane. Premium isn't any cleaner or anything like that. It may actually be older since fewer vehicles use it and it sits in the tank longer.

The GS500 runs on regular fuel...running premium doesn't help or hurt the engine, just costs you more...(no, let's not start the "octane discussion" again)...if you seem to be getting about the same mileage on either setting, then just fuel up before you hit 300kms (190miles) and you should be fine until you figure out what the issue is...if you ride agressively then maybe at 250kms (150miles)...

Later.

Quote from: Vova on March 26, 2011, 09:03:48 PM
Today I ran out of gas again. I had been running it on reserve, figuring I run out, switch it to on. Did not work!

So, if it starts and runs on both settings, and the hoses are reversed but neither appears to be acting as a reserve... what problems could it be?

When it runs out, you have to first switch to 'prime', start it up, then switch to 'res' (or in your case that would be 'on', if the lines are reversed).
This is because the fuel tap is operated by manifold vacuum, so if you run out there is no fuel in the carbs and you won't get any until its running (catch22). You need 'prime' initially as that lets fuel flow when the motor isn't running. So that could have been the problem, although your Dad's extra fuel would have had the same problem, but maybe you cranked some more and enough fuel got through while you were cranking to fire it up.

Quote from: the mole on March 27, 2011, 12:09:32 AM

Quote from: Vova on March 26, 2011, 09:03:48 PM
Today I ran out of gas again. I had been running it on reserve, figuring I run out, switch it to on. Did not work!

So, if it starts and runs on both settings, and the hoses are reversed but neither appears to be acting as a reserve... what problems could it be?

When it runs out, you have to first switch to 'prime', start it up, then switch to 'res' (or in your case that would be 'on', if the lines are reversed).
This is because the fuel tap is operated by manifold vacuum, so if you run out there is no fuel in the carbs and you won't get any until its running (catch22). You need 'prime' initially as that lets fuel flow when the motor isn't running. So that could have been the problem, although your Dad's extra fuel would have had the same problem, but maybe you cranked some more and enough fuel got through while you were cranking to fire it up.

Yes, also ruled this out the first time (first time I ran out I did not know what the "PRI" setting was, so did not mess with it) because even though it did not have enough gas to run it would catch and start and ran for ten feet sputtering and died, and did that again. So switching to reserve it would start, just not, well, run.

Also this time I did switch to prime and no go.

I am really hoping I just screwed up and was running it on "on" again and it is as simple as the hoses are messed up. A repair bill would eat into the few "extra" bucks I have laying around to get myself some boots and gloves! That being said, probably not waiting and ordering those on Monday as my shoes may already be past the point of no return as far as black toe is concerned!

Quote from: Vova on March 26, 2011, 09:03:48 PM
Today I ran out of gas again. I had been running it on reserve, figuring I run out, switch it to on. Did not work! My dad brought gas by (this was on the freeway, so embarassing ) and took a look inside- granted his experience is not on anything similar to a GS500, but he felt there should have been enough gas in there to be running.

That's how it works!  There is only one compartment for fuel.  The ON part of the petcock draws fuel from a standpipe in the tank.  When the fuel level drops below the top of the pipe you "run out", then switch to RESERVE.  That part of the petcock draws fuel from a very short standpipe in the tank right next to the taller ON pipe.  So you were using the short one until you ran out.

The GS has a flat bottom tank, and it appears that there is quite a bit of gas still in there when in fact it is not enough to get into the tank-mounted petcock.

Do this: 
Turn off the tank mounted petcock. (TMP)
Pull the hoses off the frame mounted petcock. (FMP)
Plug the hose coming from the long nipple on the TMP
Run the fuel line into a clean container so you can pour the gas back into your tank
Turn on the TMP
Fuel will run out of the ON pipe in the TMP. 
When it stops flowing, unplug the hose coming from the long nipple. 
Fuel will then run out of the RESERVE pipe in the TMP. (about a gallon)

If no fuel runs out of the RESERVE line, the standpipe in the tank is broken.

In the meantime, fill the tank, set odometer to zero and fill up again before it gets to 300km, or 180 miles.

Just to be sure, when you said you left the bike on reserve and switched to ON, you didn't switch the hoses too, right? Because that would've left you in the same spot you were in last time.

How many miles did you get this time? Was it the same as you got last time it was it 40-50 miles more/less??

I'm not sure, and wouldn't know without looking at the frame mounted petcock, but when you switch from 'ON' to 'res', does this actually stop the flow from the 'ON' hose?? I'm picturing 2 different scenarios and if when you switch from ON to reserve the bike cuts the flow from the ON hose, then this doesn't help you, but, if the petcock leaves the ON line running regardless, and simply opens up the flow to the reserve line, it would make sense to assume that something is wrong with just the reserve line on your bike, such as a clog because that would let your bike draw gas from the ON hose regardless of what position the frame mounted petcock is set to. Make sense? I know you said you checked prime before you switched, but did you just try to start it in prime?

At this point I would just pull your tank. I know it sounds like a hassle but it's not all that bad. Lift it up, shut off the tank mounted petcock with a long screwdriver(should access it from the right side of the tank with the screwdriver, if that's reversed then the petcock is on backwards), pull the hoses(outside because you'll spill a little gas), put a clean container under your tank and turn the petcock back on(cleanest method might be clear hoses and a 2-5 gallon gas can). Make sure fuel is coming out of BOTH spouts. Let it drain until 1 stops, does it still run out of the other at this point? If so you know the reserve line functions, plus you now know for sure which one the reserve hose needs hooked up to. If you got past that point next in line is to check your hoses. Either hook them to the tank and make sure gas comes out the other end, take them to your sink and just run water through them, or while you've got the tank off just spend the few dollars and replace the lines all together, who knows how old yours are. Make sure you're not just dealing with a clogged fuel line. If you get past all of this and everything still looks right your problem has to be the frame mounted petcock. If it works in one of the settings then the vacuum is still working, but you'll still need to pull it apart and see why nothing is getting through the reserve setting.

Let me know if any of that didn't make sense!

Quote from: Big Rich on March 26, 2011, 09:41:30 PM
Maybe the petcock is broken? I don't know what a GS petcock looks like, but most have a tube that goes up a little higher for the "on" setting (reserve is flush with the bottom of the tank). If the tube breaks off, it wouldn't matter which setting it's on- both will use up all the gas.

From my understanding, the bike runs fine with the petcock in either position (on/res)...so Big Rich's explanation makes the most sense...if you perform the test that tt_four suggests, pulling the tank and then using the tank mounted petcock to drain the tank...watch to see if one side stops draining before the other, if not the tank petcock is effed...otherwise you now know which side to run to the reserve inlet on the frame mounted petcock...

Later.

Alternatively, you can pull the hose at the carbs, or inline filter and stick it in a bowl.  Switch to prime and see if that works.  Switch petcock to "On" and crank over the bike.  If fuel comes out you're golden.  Now do the same for "Res".  If fuel comes out you've got another gremlin in the works......

I just did this exact thing yesterday to check fuel flow on Ju-ni. 

Thank you everyone, had to go grab the glasses to sort through so many ideas! Apparently I have come to the right place !

I think I am going to follow TT_Four's idea. It seems I could do some diagnosing before hand to try and narrow the problem down- but if the hoses need to be flipped anyway I might as well go ahead and do the whole shebang. How big is the tank on the GS500, I just filled it yesterday, am I going to have to wait for thirty minutes while it drains? I might need a siphon anyway to test after I have taken it all apart and switched around and whatnot. Though I guess by then the gas is in a container so I could just put less back in.

To answer the couple questions, I do not know how much gas I had in there and the mileage. I have left my trip meter going since I bought it (will do the math to actual miles soon so I can keep trip meter zeroed out). It was supposed to be simple, when I ran out the first time it was right at about 250miles, so I could do the math there to refill pretty easy- but once I started figuring out the problem I wanted to run out of gas so I was not filling it all the way when going out on longer rides. So no way to know unfortunately.

1- When I pull the tank is it easier to just remove it all the way off the bike? Aside from the bolts and fuel lines are there any other hoses or anything I would need to disconnect?
2- Couldn't I just disconnect the hoses at the frame petcock and let the fuel run through them, not only will I have the flexibility of the hoses to direct the fuel, but I will also be able to verify they run fine (that being said since the bike runs on both "on" and "reserve" I cannot imagine there would be a blockage or anything).
3- Is there any reason to replace them? I am hoping to do this tomorrow since I have the day off, but not sure I will get time to buy new hoses today beforehand. It sounds like replacing them would not be tough in the future. The bike is a 2004, not sure if the hoses were replaced or not before.
4- I will need some sort of open container it sounds like, one of those red plastic gas tanks won't work it sounds like because I will need to be able to let the fuel flow very visibly, and not just jam the hoses into the opening or something (so I can see which drains longer).

Okay tore into it this morning. Got the tank drained and hoses switched. The only thing that seemed off is it felt like the reserve hose was not draining at the same speed as the main hose... but when we opened up to tank for them to train faster, they were identical? Very odd. Got them installed right, the hoses had to have been flipped because the "reserve" hose was not long enough to reach the reserve on the petcock, so I swapped the hoses and got everything put back together. I ran out of gas out in the neighborhood twice I believe and switched over to reserve no problem. Would still like to test it one more time but I am pretty confident that must have been the only issue. I must have screwed up and not been running the petcock reversed last time I ran out of gas- or maybe it doesn't work that way for some reason?

One thing that seems tricky is the diagram makes it look like the "ON" hose is obvious, but reserve just sort of goes off into oblivion. On the petcock (2004 model) there is a hose going basically down, and one coming out to the right and down. Straight down is on and one on right is reserve correct? This is backwards from the tank which seemed weird (on tank the left nipple is for reserve and right for main).

But like I said I am pretty confident it is all hooked together correctly?

Got her nice and cleaned as well. I took a million pictures and intend to put up guides for both fairing removal and the tank work. For people like me, who have no clue what they are doing (but maybe people less brave than me) . I even had a fight with the fairings for a bit before I realized there were not two, but three different sized screws. Somehow last time when I removed just the one fairing I conveniently put the right screws in the right place by chance lol. So this time around I could not believe it or figure out why some screws were just not working, never thought it would have randomly worked out last time!