Fuel, what my cycle wants but can't have.

[X-ray]

Ok  by bike finally runs and drives after a year and a half,  woo hoo!   
Now my problem. 
I installed a fuel filter with no apparent problems, at first.  I have also painted my tank with flat red primer and por'ed the inside.  Now the bike seems to only run on the fuel in the lines.  More specifically, it dosen't seen to draw fuel while running. It will fill the lines over 8 or so hours and my trips are limited to about 13 miles.  Some how air is filling the fuel filter and lines but no fuel is. I assume this mean I have some sort of air leak in the fuel system BUT I have NO fuel leaks to speak of.  I have run the system on an auxillary tank with no apparent problems.  Also I have run the motor cycle with the gas cap open to eliminate the plugged air way in the cap to no avail. I have also disconnected the frame petcock and sucked on the vaccume line with no air leaks and disassembled to clean.  The carbs have been throughly cleaned 2-3 times.  My next thought was the the flat primer is allowing air pas the tank mounted petcock but this seems like a stretch. could there be a clog in a vent line? Any suggestions?  My idle does not hang and the RPM's don't increase when I spray starter fluid every where so I thought a vaccume leak was out but who knows 

Thanks

[Lukewarm Wilson]

Silly question I know but did you put the fuel filter on the correct way? as they will generally only flow one way

[X-ray]

Yup, got the arrow pointing towards the carbs in the direction of flow.
Thanks for the idea.

[trumpetguy]

Is the tank petcock (the one you can't see) fully open?

Is the main petcock on PRIME?

If you still have the same issues after checking both of those, then you have something preventing the fuel from leaving the tank (maybe a bubble of POR?).

When you ran it on an auxiliary tank, was it going through the filter?

[Berowra]

X-Ray,

How much vacuum is required to pull the fuel (in a timely manner) from the tank?  Is it possible that the flow is too restricted by this type of filter?

[ohgood]

could be. some of the filters are expected to be force fed by an EFI pump in the tank. some are not. you want (obviously) the one that isn't but I don't know a way to find out which is which to tell the truth.

I had some trouble with finding a decent filter for mine and just omitted it. no problems yet, but since i've typed that ^^ my carbs will likely gum up with tar and feathers on the way to work this morning. yay !

are you a x-ray tech or radiologist ? (always nice to know who the medical folks are   )

[X-ray]

The fuel filter is a paper element and is meant for a brigs and straton riding lawn mower.  I figured this would be ideal but aho knows.  today I went so far as to take apart both petcocks and both seem in good order, no clogs or leaks.  I even applied vaccume to each ( sucking on various outlets) while plugging the other outlets to check for air leaks, nada.  Now I've gone and gotten my self all confused with the frame mounted petcock.  I think I will install an automotive filter that I have that is glass with a screen filter, without the screen to see of the lawnmower filter is too resrtictive or if the problem is sometthing else.  Please for clarification,  the petcock  down= run/normal; forward=reserve; and up=prime? Also when priming the carbs does fuel get drtawn from the reserve line,the run/normal line, or both?

BTW ohgood I am a tech and currently in CT.  If I was a full out rad I would have bought a NEW gs!   

[LOUiE]

down= run/normal; forward=reserve; and up=prime?

yup

[Ry_Guy]

You could try (temporarily) bypassing the petcock and run a straight line from tank to carbs. That might tell you right away if it's petcock-related.

[pkhoff]

Also when priming the carbs does fuel get drtawn from the reserve line,the run/normal line, or both?

From the reserve

[X-ray]

Update:
I changed the fuel filter to a screen type thinking it would be less restrictive but the problem persisted.  I even opened the tank and attached a plug and hose device so I could pressurize and add vacume to the tank; interesting things happened but no solution.  I then went to Home Depot and bouught some clear hose so I could witness just what the hell was was happening with my fuel flow.  It appeared under low RPM air was leaving the petcock and would slowly fill the line going the carb, including the filter, starving the engine.  I then redisassembled my petcock to find the check valve on the vacume side of the diphram is buggered (gooifcation) but still allows free airflow both ways.  I greased all surfaces that might make a seal in an attempt to stop the air infiltration as well as replaced the o-ring intergral to the switch.  All checked out off the bike( the suck blow test  ).  I reinstalled with the clear tubing and ran the bike.  Same F*&$(@g problem!  SOOOooo.  I decided to clamp off the vacume line with my hemostats.  SHA-ZAM!!  no air leak.  WTF!  I left the hemostats on the hose and removed the vaccume line from the petcock and allow open air to the vacume side of the diphram with no apparent problems. 
Note:  I had this problem on prime setting also.

Conclusion:  Even thought the diaphram seems good, the apparent lack of the check valve, I think, causes the diphram to flap back and fourth as the engine fires and some how allow air to infiltrate into the fuel side of the diphram. 

I'm at a loss for a fix because it seems to work fine off the bike but when installed.... well you know. 

I am destined for a petcock mod or replacement but more importantly; Any imput as to what is going on?  Could this be the reason for others starvation issues?   
Sorry for the book.

[bikejunkie223]

I haven't ever disassembled a petcock, but generally speaking the point of a check ball/valve is to allow vacuum under some conditions, but not others and you basically have narrowed it down. Get a replacement petcock and you should be set from the sound of it.