2000 mercury 2.5l 200xl sw

[robt]

I have a 2000 mercury 200xl v6 carburated motor it has a cdm type ignition. the motor runs great at idle and at top end (will turn 5800rpms on a 21 foot boat) at 2000 to 2500 rpm the motor will slowly start to die the rpms will fall steadily till the motor just dies, it will then restart and run like nothing happened, it only does this half the time, if you catch it just before the motor dies and snap the throttle open it will pick back up and run, also if u push the key in and choke/prime it. i have gone through the entire fuel system and replaced all lines and primer bulb, also checked for air leaks and cannot locate any... plz heelp any ideas- thank you.

[boats.net]

Have you tried pumping fuel primer bulb to see if rpm's pick back up? Is the primer bulb being sucked flat(a fuel restriction)? Might try loosening the gas cap to see if have problem with tank vent, might even try running on a 6 gallon portable gas tank to rule out a fuel problem in boat fuel system.

[robt]

i have checked tank vent and delivery line ok . cleand carbs n rebuilt fuel pump. still wants to bog n die at 2000 rpm will idle and run high speed 5800rpm thank s for any reply robt

[boats.net]

Looks like you have gone through entire fuel system but It does sound like a fuel problem. Bumping choke makes an improvement then it makes me think there is still a fuel problem. Have you tried pumping fuel primer bulb to keep it from dying? A loss of manifold vacuum can affect fuel pump so look for a bad intake gasket, you can spray silicone spray at manifold joints while engine is running, if there is leaking gasket then rpm's will usually increase at the spot of leak. Make sure check valves inside fuel are sealing properly.

[robt]

do you mean inside fuel pump check valves

[boats.net]

Yes check valves inside fuel pump they become deformed and don't seat properly.

[robt]

ok will ck them thank you for input