Engine Synchronizer Gauge issue

[Troy M]

Was hoping to get some insight on this. When I have an equal synch gauge reading, my port engine is at 3200rpms, which is has always been normal. However, my starboard engine is running 4000rpms. It's happened the last 2 outings, and not sure why. No problems with getting on plane and both engine temps exact at 170. Why is the starboard motor working harder to match the port motor? Can uneven outdrive trim cause this? Or is the rpm gauge lying to me? Thx!

 

[magstang1]

It sounds like either your sync or one of your tachs is lying.

You could possibly be cavitating a prop causing higher rpms, but your sync should show you this.

I would think you would be able to hear the difference between 3200 and 4000. Does everything sound normal?

 

[AFD]

definitely a gauge problem. here is your real problem though...which one!

 

[Btcowboy]

I have same issue on my 94 290 DA. Mine is not out as much as yours but I do find that after a while they do begin to match

 

[brightman27]

I just bought an 88 300 weekender with twin 5.7 straight shaft props...was just getting ready to post this same problem except my sync gage points all the way to port....luckily the guy I bought it from gave me a complete set of new gages,so last night I installed the TACHS and sync gage and new style sync module,which is a square small box with wires coming out of it that you wire directly to ur TACHS and power and ground...got done late last night so only ran it in the dock in neutral. The TACHS seem to be reading a lot better but if ya increase either engine the sync never changes...only ran revs up a little but it never moved off center....read somewhere that the new module only starts working after 2000 rpm...anybody done this new set up? Also on ur old tacbs there's a calibration screw that you can adjust but ya need and optical tach to make sure ur on...any input on the new style module?

 

[brightman27]

put two new tachs and a new style sync module and sync gage on my 88 300 weekender with twin 5.7 inboards...the tachs read the same now but the sync gae stays pretty much right in the middle no matter what...guess I'll quit worrying and keep on boating....if the tachs read good dont know why ya need the sync gage anyway