Suzuki DF175 surging at high power setting

[Jeff J]

Just started getting a 1000 rpm surge at high power settings going across the lake. Not feeling a miss. I think about 1100 hours on the motor.
- Replaced the low pressure filter. No change.

Tank run with no load shows:
- High pressure side reads 70 psi when the key is turned on and 40 psi after the motor is started (checked at idle and 4000 rpm). No problems while checking.
- Low pressure side reads 7-8 psi up to 3500 rpm. I believe my pressure gauge connections restricted fuel flow enough to keep me from running faster. My tee reduces line size to 1/4”.

I am looking for ideas as to the next troubleshooting step.

Thanks

 

[Jeff J]

Replaced the high pressure filter and ran on the lake today. No change.

I guess it could be going into a guardian mode but not getting any alarms or lights.

 

[legalfee]

I had a 400 RPM surge over 4000 on my DF115 and I replaced the plugs and it went away.

 

[Jeff J]

The guy needed the trailer for a different boat so he took it back to the lake before I had a chance to fiddle with it again. He sent me a video showing the boat was running fine. I did notice the tach reading a good bit past 7,000 rpm even though the engine sounded normal.

SDS arrived today. Haven’t gotten it out of the mailbox yet but now I think the computer is getting a bad signal and reacting accordingly. I wish I had more experience dealing with sensors and computers. It helps on the rare occasions something actually throws a code but I don’t know how it all ties together to know what’s wrong just reading the engine parameters. Based on past experience, I don’t think a lot of trained techs do either.