'05 500 issues

[wodyson]

Ok so let me give an update of what i did today.

One major discovery was that my float bowls were empty, so that explains why it sounded like it was out of gas when i cranked it.

I fed the fuel line leading into the carb bowls and put the carburetor back in place. When I cranked it it would run for about 3 seconds and then die. So I plugged a clear vinyl tube from the petcock into the carb to make sure the gas was flowing into the carb. when I cranked it there was no gas flow.

I wanted to test the petcock so i unplugged the clear vinyl tubing from the carb and put it on PRI and gas flowed through.

I unplugged the vacuum line from the petcock and made sure there was a vacuum which there was.

I pulled off the petcock again and checked to make sure everything looked good, which as far as i can tell it did, everything was clean, except the membrane was lightly white, but not something that came off, but didn't seem restrictive necessarily.

So why does the bike start for a few seconds and then die when the float bowl had gas in it? Also why does gas not flow from the petcock into the carburetor.
Another thing that seems weird is that I didn't realize on the tank petcock that on position is actually in between the screw twisted all the way left or right. But this whole time i had been riding with it turned all the way to the right, that was 2 weeks, why did fuel flow during that time and then all of a sudden stop?

After doing all this i feel much more enlightened on how my bike works and much more confused on what the problem is.

[Kerry]

First of all, kudos for "digging in" and trying several combinations.    I think we're getting somewhere, and the detailed data helps a lot.

So why does the bike start for a few seconds and then die when the float bowl had gas in it?

The fact that it runs at all tells me that your jets aren't clogged; that air coming from the air filter and through the carbs is appropriately sucking fuel from the float bowls (through the jets), atomizing it and supplying it to the cylinders.  That's good! 

Also why does gas not flow from the petcock into the carburetor.

Ahhh.... there's the rub.  If fuel can't get into the float bowls to replace fuel that's being "sucked out" by the airflow, it's reasonable to assume that a kind of vacuum would build up and prevent further fuel from being "sucked out" of the bowls, even though the bowls have fuel in them.

I'm not intimately acquainted with the '04+ carbs (I've never seen one up close) but I have two ideas.  I'll be referring to [THIS DIAGRAM] as I go.


1) There may be a blockage in the fuel delivery system.
You may want to inspect the "T fitting" where the hose from the petcock attaches.  (Diagram item 48)  I suspect the "T fitting" because the problem seems to be affecting both carbs.

If that fitting seems clean (you can blow air through it) you'll need to work your way toward each carb from there.  It would be great if you had access to the "carb end" of each of the tubes that connects the "T fitting" to the carbs ... but I doubt you will.  Perhaps you can shoot some carb cleaner into each tube, stop up the open end with a plug of some kind, and then "let the cleaner work" for a while?  You may need to repeat the treatment a few times.


2) The float needle valves may be stuck shut.
It would be odd for BOTH valves to be stuck shut, but I guess it's possible....  How could they have gotten stuck shut?  Hmmmm.  Getting gunk in the float seats tends to make the valves stick open, not shut.  Is it possible that you fiddled with the float assembly (Diagram item 24) or the needle valve assembly (Diagram item 21) when you had the float bowls off?  What we're looking for is floats that are either stuck, or set (way) too low.

You kinda have to think backwards when it comes to the floats ... because you usually only tweak them when they're upside down on your workbench.  But if you think about them "in place" in the bike:

       The height at which the floats are set determines the average level of fuel
       in the float bowls.  Obviously, the floats actually "float" in the fuel in the bowl.
       The metal tab between the floats moves along with them, so when it contacts
       the needle at the top of the float chamber it closes the valve and stops the
       flow of fuel into the float bowl.  As fuel is "sucked out" of the bowl through the
       jets, the fuel level drops, the valve opens, and more fuel is admitted from the
       petcock.  This raises the floats, which closes the valve ... you get the picture.

       When the floats are set really low (meaning that the metal tab between the
       floats is bent significantly upwards ) the valve closes when there is a relatively
       small amount of fuel in the bowl.

       If the tab is bent downward it doesn't close the valve until the floats have risen
       higher - meaning that more fuel has been allowed in - so the fuel is kept at a
       higher level.

As you can imagine, this is a rather delicate assembly, meaning that a very minor tweak can result in a large swing in the float height / fuel level.  If you suspect that any inadvertent "adjustments" have been made ... it may be time to pull the carbs and do a proper float height adjustment.

Another thing that seems weird is that I didn't realize on the tank petcock that on position is actually in between the screw twisted all the way left or right.

Oops!  Well, sillier things have happened to all of us, I dare say.

But this whole time i had been riding with it turned all the way to the right, that was 2 weeks, why did fuel flow during that time and then all of a sudden stop?

Whoa ... chalk that one up to "anti-gremlins" or something!

After doing all this i feel much more enlightened on how my bike works

Glad to hear it!

and much more confused on what the problem is.

S'OK ... hang in there! 

[wodyson]

uuuughhhh. so i had a little bit of time to play around with the bike today.  i didn't have a small enough clear vinyl tube to test the float height with, and i didn't really have the guts to pull the 2 carbs apart to check the T fitting of the fuel delivery, because of all the other things involved in getting them apart. but manually fililng the carb from there (by simply pouring gas in the T fitting) worked, so i was figuring and hoping it was clean.  I blew on the (item 49 from the diagram) carb breather? and noticed that it looked like the jets rose? or maybe gas was just moving up them, i couldn't tell, and gas came out of the T fitting of the fuel delivery of the carb. I didn't have carb cleaner, and i'm not sure if i any longer have time to work on it now that school is tomorrow... any way
i put everything back together and put the bike on PRI and heard gas flowing! i was excited to ever hear that as i couldn't before and cranked the bike and it started! and kept going! i can't explain how good it felt to get back on the bike...but...

i was riding now (first ride since it started working) to church and i was feeling very light lurches, so light that i was having a problem telling if it was just small bumps in the road, or if it was having problems again. anyway it seemed to go away, i drove about 5 miles and arrived at church. was there for about 2 hours. on the way back it went about 3 miles and then started lurching and then died while approaching a red light, i started it back up before it came to a complete stop without a problem, went another mile and there were noticeable lurches, i would pull on the throttle and it was not really responding, lurched a few times then died. i pulled over and PRImed it started it back up and got to my house (half a mile away).

now i'm very drained from thinking it was working and then this again. school starts tomorrow and i will have no time to work on it but i need it to get to school for parking reasons (no car parking). i really want to figure out what the problem is, and i'd really like to do it without taking it into the shop. but i think i'm just gonna have to try and get it up there.

[Kerry]

i didn't have a small enough clear vinyl tube to test the float height with

Yeah, that stuff took me a while to find....

and i didn't really have the guts to pull the 2 carbs apart to check the T fitting of the fuel delivery, because of all the other things involved in getting them apart.

Can't say as I blame ya!  They keep adding more and more "stuff" around the carbs as the years go by.... 

i put everything back together and put the bike on PRI and heard gas flowing! i was excited to ever hear that as i couldn't before and cranked the bike and it started! and kept going! i can't explain how good it felt to get back on the bike

Nice results so far....

...but... [...] lurched a few times then died.

Grrrr!

i pulled over and PRImed it started it back up and got to my house (half a mile away).

[...] school starts tomorrow and i will have no time to work on it but i need it to get to school for parking reasons (no car parking). i really want to figure out what the problem is, and i'd really like to do it without taking it into the shop. but i think i'm just gonna have to try and get it up there.

So, would you say that the bike runs well (no lurching or dying) in the PRIme position?  If so, that's what I would do as a stopgap measure until you have a long enough break to do some more work on it.

The problem with taking it to the shop is:
  * It will cost a lot
  * It will most likely take a long time
  * It may come back no better (or even worse) than before

If the bike runs well in the PRI position, the final solution may be as simple as replacing the fuel selector (ON / PRI / RES) switch.  In the meantime you can just switch it to ON when you park if you're worried about possible "flooding".

If it doesn't run well in the PRI position then your options do become somewhat limited ... since you need the bike for transportation. 

[bval]

You may have been through this already, but the petcock position is crucuial. O have an '06 GS500F and after taking my tank off for the first time, I forgot to replace the petcock shutoff to the correct position. The bike started fine, idled fine and ran fine - for a few minutes. Then it started lurching. It would idle fine, but wouldn't rev without sputtering. I popped the back of the tank up and turned the petcock shutoff to the vertical position, in other words, with the screwdriver slot going up and down. No problem after that. Might be worth checking again as it will be a problem if the slot is in a horizontal position.

[wodyson]

just wanted to give a quick update. i rode the bike on RES for 40 miles last night and didn't notice any problems... so i think i'm gonna ride it to school tomorrow and hopefully still not have any problems eh? so maybe it is in fact just the petcock switch?
what would be a good way to test conclusively that that is indeed where the problem lies?

[bval]

Again, you may have already done this, but have you checked the filter screen inside the tank yet? I remember earlier in this thread you said you had the petcock apart, but I'm wondering if it included the filter screens. It could be that the filter screen inside the tank is gummed up by dirty fuel, warter, etc. It might explain the intermittent nature of your problem as  the filter can be partially plugged and partially working, but would get either worse or better as things slosh around in the tank and/or the fuel level changes.

You can either take the tank off and remove the petcock and filter, or possibly try back flushing gas through the petcock. In either case, I'd then use some fresh gas to swish around in the tank and dump it out several times to make sure any gunk that is backwashed out of the filter is removed from the tank. But I think the best thing to do though is remove the tank and the petcock completely.

[wodyson]

Yea i checked the filter inside the tank awhile ago by taking it out, and it was clean. I also as best as i could, using sunlight, checked the inside of the tank but it all looked clean. But I will when i have a chance take another look at it. Also I am not sure about all the functions of the petcock and how it really should look, but from taking that apart it seemed to be really clean too. Well right now all i can do is keep my fingers crossed on the way too school till i get a chance to check it out i spose...