So I bought a 2000 f4 a few months ago I test rode it around the block and it ran great, a few days later after I’d gotten it home and actually rode it idles great revs well in my driveway and got the bike to speed I noticed it had a nasty cutout/stumble while trying to maintain consistent throttle around 60mph or so I then removed the carburetors which were fairly clean I cleaned all jets and needles and the bike runs really good no more sputtering or cutting out while maintaining consistent throttle

however what it does now is when I go through (for example) 1st-2nd-3rd at red line then let off the bike will run like it’s starving for fuel for 10-15 seconds after the pull goes right back to running great. I replaced the fuel filter when I cleaned the carbs and that looked good the inside of the tank looks great so I assumed maybe it needed new plugs changed those no change so today I figured it had to be the fuel pump because I do not hear the pump prime when I turn the key on and I cannot feel or hear the pump running (because my bike is super loud) so I pulled the fuel lines and started the bike fuel immediately came from the hose at a good rate

I did some research and found that the fuel pump gets pulses of 12v at idle and below 20mph and constant 12 above 18-20mph and was instructed to put my bike on a stand and check the output of the fuel pump above 20mph and the output looked better at idle than above 20mph but it still produced fuel

I should add that when I jumped the solenoid for the fuel pump it worked as should and was audible

I appreciate any and all help or feedback because I’m stumped as to if I need a fuel pump or not

 

I would check the vent line from the tank first - make sure it's not blocked etc.

 

I will certainly look into that and look at the diagram in my manual because as of right now the only line coming from the bottom of my tank is my actual fuel line coming from the petcock I’m unaware of others, the bike has had a few owners now and definitely some questionable work has been done to it so I’m sure that vent line has been disconnected for awhile I’ll definitely look into that

 

Any advice in how to clean the tank breather?
I tried feeding a pipe cleaner from the bottom but suspect this isn’t optimal.

 

just put my new fuel pump on and the bike wouldn’t even run on all 4 cylinders switched back to my old pump and the bike runs again so I’m stumped, the only thing I can find on the bottom of my tank that looks like a breather leaks fuel if I don’t have it plugged