250 optimax pro xs random lazy throttle response

[Wfochris]

Serial # 1b882351

Had new power head put on around 2016 or 17, has roughly 50 hrs on the powerhead, engine is on a 2012 ranger z521, boat will run fine then when I go to take off and shove the hot foot down the boat doesn’t accelerate I can start to back off the pedal and it will take off and run fine. Things I have done so far is replace spark plugs and wires, replaced vst filter, checked fuel hoes it has the correct epa fuel hose’s and the inside of the hose looks like new. Are there any other obvious things that would cause this

[JOE54]

so it idles fine then when hot foot is depressed to wot it bogs until you start letting off hot foot then engine revs and starts to accelerate , on plane what is wot rpm full trim max throttle ?????

[Wfochris]

Yes idle seems fine and wot to take off doesn’t accelerate once I back off throttle it accelerates and takes off, wot rpm is around 5,700 to 5,800 on the smart craft gauge, boat has a 25p tempest plus.

[lpugh]

Sweep test the TPS sensor.
Range test intake air temp sensor
Test available voltage from each coil with kv tester.
check air/fuel pressures.
Verify prop is vented to achieve 3600 to 3900 during hole shot before nose over happens.

[JOE54]

my opinion also the way it sounds from here

[EuropeanAM]

Good suggestions above.

One other item I would add to the list: Try a known-good MAP sensor (you can even borrow one from a friend's similar motor). Sometimes a small bubble of oil gets up inside the sensor and they get "really lazy" as that oil/bubble dampens the reaction of the sensor.