I have a 1999 CBR 600 f4. For some reason it keeps flooding itself and fuel is dumping into the Carburetors while fuel supply is off but only does it when you twist the throttle. Please help!!

 

If fuel is getting to the carbs from the (working) fuel pump, thats fine and normal. The pump will push fuel even if the petcock is set to off cause there is still fuel in the lines. I hate to say it but you'll need to pull the carbs and check all four needle valves and the floats to find the stuck one. I say one cause its almost impossible that all four carbs have a problem. The only other possibility is the fuel drain screws on the bottom of the float bowls. You only have to remove the float bowls to check these once the carbs are out. It may in fact just be a hunk of funk in there causing it. A proper cleaning is a good idea while your in there. Good luck!

 

+1 on float valve. Even if it looks good get 'er clean

 

Is there a petcock on the F4? If so where?

Thanks

 

Yes, there is. Its to the rear of the tank, accessible by reaching under the left side. The F4's petcock setup is an *always on* type setup.

 

What is the use of a petcock if it is always on?

 

When you do maintenance that requires the removal of the tank or no fuel flow, its a good idea to turn off the fuel. ;-)

 

Here is something that you can try. Turn off your fuel at the petcock. Then open the drain screws on the float bowls to drain all the fuel out. This will cause the floats to open up all the way, which in turn opens the float valve all the way. If there is something small stuck that is keeping the float valve from closing (which causes the carbs to flood), this may free it up. Close the drain screws on all the bowls, open the petcock and then try starting the bike. It may be hard to get it to start the first time since there isn't any fuel in the carburetors. It's hard to say if this will work or not, but it's a shot in the dark. If it does, it probably wouldn't hurt to drain the bowls again, since whatever was stuck, is now in the bowl and you don't want it to get into the jets.

Good luck.