Can't drain tank through petcock - - Why??

I'm in the process of removing my carburetors for a good cleaning (actually soaking) on my 1993 CBR F2, and of course removed the tank first.  The fuel level was on reserve (barely) so the tank would be light.  I thought I'd check the flow through the petcock to see if the screen was clogged without dissassembly.  I turned the petcock  back over to reserve again (had turned the setting to stop before tank removal), and nothing comes out.  Not a drop.  I shifted the tank in every position imaginable and cannot get a drop of fuel to come out.  Why not?  I do have CV carb's and does that mean no vacuum equals no fuel?  Or....is the petcock goofed up?  Probably just need to remove from the tank and see if the screen is clogged up?  Hate doing anything I don't need to though.  A quick second question - - -  has anyone put a fuel filter on their F2?  If so, where did they get it?  Local auto store OK?   Third quick question - - - I've exposed the carburetors and want to remove and clean as an entire unit (don't want to separate into four units and bag and label a ton of stuff, if possible.  Any down side to that?  There seems to be a ton of lines, hoses, etc. to deal with otherwise.  Can everything but the rubber diapragms be soaked in carb cleaner safely???  That's it.  Thanks from those who are in the know!!!  Appreciate the time.
 
JP

I turned my F3 tank on it's side and removed the petcock.  Don't know any other way, bro.
 
As far as fuel filters, get a high-flow, inline filter for like $4 at a parts store.  Install it in the line just after the petcock (give yourself enough hose to make it serviceable).

it's a vacuum actuated petcock valve silly. you need suction on the vac line on the petcock in order for it to open!

hmm thats odd they didnt keep that feature for the f3. I remember taking my fuel tank off of my f3, accidentally hitting the petcock, and having fuel everywhere.

The F3 petcock doesn't have the vacuum release...  the F2 factory unit does (although it will work with the vacuumless "cheap" replacement petcock).

I still wonder why honda took that feature away?

Probably to save money, to simplify it, or because they deemed it unecessary.

not that it really matters to the thread anymore, but are you CERTAIN the petcock on the F3 isn't vacuum actuated? I'm seeing a fuel line and what appears to be a vacuum line on RonAyers.com...

**Actually, i now see a very small fuel pump. NM then**