Fuel Starvation

[Novas86]

Now i know that there are probably other threads and i may catch flak for asking this problem but please humor me. 

I bought my 05 about three weeks ago and just today on a long ride in the on position on the petcock it wanted to die like it had no fuel though there is fuel in the tank.  I have read that there are lots of people with the same issue but not finding any answer or ideas on how to fix it other than change to aftermarket one or to just run in prime mode.  So for those who have had this problem how did you fix it?

[jeremy_nash]

when that happens, you need to switch it to reserve, then go to a gas station and fill the tank up.  with the shape of the bottom of our tank, it looks like there is more gas in it than there really is.

[Novas86]

lol no I had literally just filled about 40 miles before that

[jeremy_nash]

if it does it again, try opening the gas cap, and see if that fixes it.  if that does the trick,  follow the steps in this thread.
http://gstwins.com/gsboard/index.php?topic=41061.0

the fuel starvation issue is generally reserved for the older petcocks.

[black and silver twin]

make sure the vacuum line to the petcock is attached and not cracked.

[Novas86]

So i decided to take apart the gas cap and the ball bearing seems to move very freely.

I haven't checked the vacuum line off the petcock yet for cracks just yet but i will. Please keep ideas coming no idea too stupid minus gas in tank lol jk

[Novas86]

make sure the vacuum line to the petcock is attached and not cracked.

If i take the vacuum  line off the petcock to check for vacuum how much vacuum should i feel?

[black and silver twin]

most engines idle at 20-29 inches of mercury. you wont be able to discern 10 in from 29in without a gauge. but if the line is not cracked or plugged it should be fine.

[Novas86]

unfortunately i do not have a vac gauge anymore atleast not where i am at currently.  Any other options btw i have only owned this bike for 3 to 4 weeks and haven't gotten to ride it much its my fifth bike and smallest and first Suzuki (started on a Ninja 600 like the one Tom Cruise rode in Top Gun lol).  So being I am so new to this GS stuf please if there is something i am missing about them inform me I am a noob to them but not a noob to working on bikes

[black and silver twin]

also make sure the gas tank vent tube is not clogged

[Paulcet]

(started on a Ninja 600 like the one Tom Cruise rode in Top Gun lol). 

Just picking nits here, but the Top Gun Ninja was a GPZ900.  Well, I read somewhere that it was actually a GPZ750 with 900 markings because the 900 wasn't ready when they shot the movie.  Can't find that reference at the moment.

Oh, as for the problem at hand, does the problem happen if you run on 'prime'?  That would diagnose a vacuum line problem.

[Novas86]

no atleast not on the surface i ran it yesterday that way to get home however on the way to where i was going i was switching between the two and it was still dying.   freakin weird right

[JAY W]

Had the bike been used on a regular basis before you brought it,if stored it might need carbs,jets cleaning,fresh fuel?

[Novas86]

It had been parked for a little bit and the guy i bought it from put i think i was a seafoam in it for he winter but other than that i don't know

[Toledo Jim]

I suggest that you drain ALL the old gas out, along with any water or other contaminates that may be in the bottom of the tank.

If it looks and smells good, use it in your lawnmower or something.

Fill the tank with known good gas and try again.

I saw a tank a couple of years ago that had almost 2 inches of water in it.

Worth a try?

Jim

[Novas86]

I just checked the vacuum line and it seems good and i pulled it off the petcock line and it is getting vacuum and seems fairly strong like stick to my finger strong i don't have a gauge to test it for certain but any other theories?

[jeremy_nash]

cap one of the lines off at the tank, and run a single line from the tank directly to the carbs.  that will completely bypass the entire vacuum  operated petcock

[Novas86]

to test to if its somewhere else in the vac system?

[Novas86]

update : I unplugged the vacuum hose to the petcock and it died just as it dies on the highway. which leads me to believe its a vacuum issue.  Can someone please explain the purpose of the vac system in this bike cause my r6 used vac for fuel shut off in case of emergency and so did my ninja.  so please forgive my ignorance

[black and silver twin]

the vacuum system is used to automatically stop fuel flow when you stop the engine, so you dont have to turn the petcock knob. if the petcock is not receiving vacuum or has a torn diaphragm it will flow little to no fuel, causing most (if not all) of your symptoms.