DF20A not revving

[AmbiPM]

I have had to deal with some modern four stroke small outboards from suzuki and I am a little confused with all the extra sensors and the fuel injected system. I would really appreciate some help.
I have a problem with a DF20A . Few months back there was some water in the fuel tank and it got into the fuel lines and the pumps etc. So I cleaned the whole line by draining all the pipes the pumps etc and I checked that both pumps were pumping fuel when I put fresh fuel and bled the lines. I also checked that the injectors were spraying fuel like fine mist.
The engine ran for a few hours over several weeks without any problem but now suddenly it does not rev up to full throttle. It has a super smooth start and holds idle very well but the moment I raise the throttle more than half and hold it there the engine speed oscillates between fast and slow revving up and down once every second.
To my sense and logic it sounded like there was not enough fuel passing through to maintain the high rev but am not sure.
Any help is appreciated. Thank you.

[2014DF25ARS]

The behavior you describe, i.e. "revving up and down once every second" sounds to me as though the engine is being rev-limited by the computer. The two reasons I'm aware of that it will do this are:
(1) You're exceeding the rev limit = probably somewhere around 6k RPM
(2) The computer thinks the engine is in Neutral. It will limit revs to something like 2-3,000 RPM when the engine is not in gear.

I'm not familiar with the DF20A; I have a DF25A. And you don't say whether you have a tiller model or remote model (mine is remote). On my motor, I can produce the behavior you describe if I start my motor and raise the "fast idle" lever on the remote control without putting the motor in gear. There is a "neutral switch" in the motor that tells the computer when the engine is in gear.

[AmbiPM]

Thank you for that info and sorry I did not mention that mine is a tiller model.
The rev was not close to 6k so I guess your second option explains it.
Let me try checking on the neutral switch which could have failed.
Thanks a lot.

[AmbiPM]

You were right with the computer limiting the rev.
Thanks a lot.
now if you want to hear the funny story. ...
The guy driving the boat gave a complaint that the engine wasn’t working. I checked the tank and found water inside so I bled cleaned and serviced the pumps. After fitting I asked the guy to keep the moorings and engage the heart and check but smart as he was he untied all mooring lines and started the engine. Engaged the gear and says’See same problem’
i took my other boat to tow him back and changed the prop in two minutes. It was a problem with the propellor... a two minute job and I wasted two days on it thanks to miscommunication’s.
anyway thanks a lot for your info. I will remember that for the future.