Crusader 454xl starving for fuel

Is it a carb or injected engine?

Not having had anything to do with that type of system although I am a mechanic by original training I did a bit of googling.

This came off a car site but I would say applies equally well for a boat.

The throttle body provides the control of air and fuel injection so that the system runs efficiently and does not backflow. When this part is not working correctly, or its electronic sensors begin firing off readings to the onboard diagnostic computer showing problems, it can create car problems. Not only does a malfunctioning throttle body have the capability to cause the check engine light to come on, it can also cause other sensors to overcompensate, causing other problems elsewhere. Typical related issues will include the oxygen sensor and the mass air flow sensor. As a result, automotive diagnostics of a troublesome throttle body can include a process of elimination with other parts as well.

Read more : http://www.ehow.com/how_8009160_throttle-body-injection-troubleshooting.html

Cheers

KIWI

i assume you have the 454 xli engine which is throttle body.as my 1997 carver 405 does.
there are 3 fuel filters before the throttle body. since you just said "i changed the fuel filter" i dont know if you did all or what. there is a oberg round black "ufo" looking filter with a screen that you open up and can clean. you also have a water seperator filter and then the cannister filter beside the throttle body. any of these can be an issue. have you gotten to all of these? or one? there is also a inline anti siphon valve on top of the fuel tank that could cause a problem if blocked. the last thing could be electric fuel pump but i would check everything before this first. pls post your finding when problem is solved

Ober filter will be first look for black disc like filter nut in the middle of it. Turn off fuel put a container under it to catch gas and unscrew bolt off. Separate it and you will see the screen remove this and clean it. Reassemble when done.
The antisipjoin is right on top of the tank.it screws on the fitting on the tank. Fuel line connects to it. Remove it and check for debris. Do this after the filters cause I bet you have issues with filters. If you have another tank just change the valve to rule out this part. Have changed water seperator? Cannister filter?
I've gotten spoiled I guess my carver 405 has plenty of access to both engines without any issues. Looks like you might have a 355 or so?

Sounds like you have water in your tank. My 355 with 454s did the same thing. Ran fine up to 2000, over that it would break up. I switched over to the port tank and it cleared up immediately and held 3200rpm all day. My problem starboard tank was found to have water/from ethanol lying on the bottom of the tank. The pickup pumped it to the overwhelmed water separator and to the engine. I had tank pumped and fuel filtered/polished and put back into tank.