2000 3.0 Mercruiser boggs down and quits just as boat begins to get up on plane

[Flymedic]

With engine warmed to normal operating temperature, Initial acceleration sounds and appears strong, just as boat reaches plane engine boggs down like it is starving for fuel, if you pull back on throttle to idle engine runs rough and sometimes will remain running sometimes not. If it dies, restarting is not an issue will restart and idle normally. Repairs to this point new fuel pump last year, this year new spark plugs correctly gapped, new spark plug wires, new rotor button, new distributor cap, new fuel hose from tank to fuel pump,
fuel filter in fuel pump checked and is clean with no debris, filter at carburetor is clean.
Removed old fuel from tank and replaced with fresh fuel and marine stabilizer. Carburetor checked by a technician inside is good all ports open, accelerator pump in good condition, no issues found internally. I am stumped anyone have any ideas???????

 

[Rick Stephens]

Time to hook up a vacuum/pressure gauge and check fuel pressure and or vacuum. Probably more effective when looking for a problem to hook up the gauge between fuel pump and tank and see if you are pulling a vacuum there, which would indicate something is plugged up. If on the pressure side of pump you want to 4 to 6 PSI maintained.

Also check that the tank vent is open. Seen a few of those with wasp nests in em.

 

[Flymedic]

Vice Admiral, thanks for the thoughts, did pressure test fuel pump and vaccum tested from tank to pump. Fuel pressure was good just a hair above 6 psi, no vaccum from tank to pump, disassembled check valve going to tank and cleaned, checked siphon tube it was clean as a whistle. Ultimately I decided to rebuild the carburetor because it was the only thing I had not done yet. And what you know took her to the water and tested Monday she ran like a champ. Now to move on to some chattering rocker arms I discovered during the test. Thanks again I learned a lot about my engine