Mercruiser 5.0 misfire and stalling NEED HELP

[Larson212]

I have an 01 Mercruiser 5.0 with a 2bbl carb and thunderbolt v ignition, boat is bone stock, recently I have developed a misfire above half throttle, I found a loose battery terminal so I replaced both terminals, I also replaced plugs, wires, ignition coil and rebuilt the carb, I have a cap and rotor on order but mine looks okay, I ran it in my driveway for at least 30 straight minutes, half at 4k rpm and half at idle, it seems after all that the problem has worsened, now I’ve been flooding at low rpm’s and the misfire has gotten worse, idk what else could be wrong, I need help to determine what else could be causing this, I’m at a loss

 

[flashback]

Possible water in the fuel.

 

[Larson212]

Possible water in the fuel.

I installed new fuel water separator with a clear drain bowl

 

[flashback]

Don't run it at 4k on the hose. Maybe the carb needs more work if it's flooding.

 

[Larson212]

Don't run it at 4k on the hose. Maybe the carb needs more work if it's flooding.

I’m almost thinking new carb at this point, it’s almost like this carb has failed

 

[Scott06]

I’m almost thinking new carb at this point, it’s almost like this carb has failed

I would rebuild the one you have with a quality rebuild kit like like from Mike Carb parts. If it is flooding the needle and seat/float are not working or you have too much fuel pressure

 

[Larson212]

I would rebuild the one you have with a quality rebuild kit like like from Mike Carb parts. If it is flooding the needle and seat/float are not working or you have too much fuel pressure

I put the old float and needle back in and I got rid of my flooding problem but I still have a misfire under load, my fuel pressure is right at 7psi I tested it

 

[Scott06]

I put the old float and needle back in and I got rid of my flooding problem but I still have a misfire under load, my fuel pressure is right at 7psi I tested it

Did you clean the carb or just put the needle and seat back in? If under load is power valve and plunger moving ok? Float level set correctly , clean the carb in an ultrasonic cleaner and rebuild.

Have you checked under load with a timing light that it isnt missing?