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1999 Searay 330EC - do I believe the Tachs or the Synchronizer?

Guest Contributor

When I am running, the tachs are off by about 300 RPMs but the synchronizer shows dead center.
Which do i believe and any ideas on how to test this?
Fix this?

Also the throttle handles are off a little bit and its annoying.
Ideas to resolve?

Please help!
Thank you.


Rising Contributor

The sync gauge is a null measurement and is the most accurate means to ensure the engines are running at the same RPM.

The throttle levers should be at about the same position during operation. That will be attained when properly adjusting the throttle cables. My Mercruiser Factory Service Manual (FSM) has detailed throttle cable adjustment / validation procedure that looks to be complete and accurate. Always follow the FSM.

Wingless good to hear from you again.  The throttle positions are annoying but my main issue is the tachs show 200 to 300 difference in RPMs.  Do you think the synchronizer is more accurate or the tachs?

I wonder where the sync gets its data from.  i looked at the wiring diagram and believe it goes to the ECM.

Thanks so much. I took several weeks off for an out-of-town family vacation.

Really enjoyed myself. I brought my plumbing and wiring tools and was swapping sinks, toilets and receptacles from FL to NH. Unfortunately will never be fully qualified as a plumber because I will never have a sufficient exposed butt crack, but I still attain acceptable results.

Yes, the sync is waaay more accurate than the tachs.

No butt crack needed!


Guest Contributor

Your ears should tell you if your running in sync.  300 RPM would difference would yield an audible harmonic in balance.

thank you......just ordered the Fox Engine monitors that I received a response from another forum.

Cant wait to put them on next season.