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

Royalboater

Royalboater

New Member
Sep 28, 2022
8
New Jersey
Boat Info
Searay 330EC 1999
Engines
454 Mercruiser inboards
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.
 
The only way to know for sure is with a stroboscope. That said, my money is on the sync gage for accuracy. You could also swap the wires on your tachs and see if the offset moves. If it does, that should eliminate the sync gage as the culprit, but won't tell you which tach is wrong.

My throttles are not even as well. Drives me nuts, but apparently not nuts enough to tear apart the binnacle.
 
I asked the same question when I bought my 330, the previous owner replaced the tachs for this reason and they are still off. I go by the syncronizer guage, it seems to be accurate based on the sound of the engines. My port tach is about 300 lower than starboard side?
 
Rizzman said:
I asked the same question when I bought my 330, the previous owner replaced the tachs for this reason and they are still off. I go by the syncronizer guage, it seems to be accurate based on the sound of the engines. My port tach is about 300 lower than starboard side?
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Yup, you will know by the sound. If they are synchronized at cruise you will hear a smooth engine drone sound. If they are slightly off, you will hear a wavering droning, a consistent wavering. Like tuning a guitar using the 5th fret, if you know how to do that. When you get the string close, but not exactly right, you hear a wavering tone from the slightly misaligned sound waves.
 
My Tacs line up with sync gauge but my throttles are at different positions, makes my OCD itch. That's why I'm installing Fox Marine gateways next season so I can see all digital readouts on my Garmin.
 
I've never had a boat where the throttles matched. The DTS boats are probably different, but little nuances like a stretched cable or different routing from one side to the other could affect it.

My sanity check on our 410 is fuel burn. If both engines are taking nearly the same fuel on fill up, I don't worry about it. If one side burns significantly more then it warrants further investigation. That requires separate fuel tanks, obviously, which our 290 didn't have.

Keep in mind the fox gateways are reading injector pulse frequency and the fuel flow the computer is asking for, not actual fuel flow like a flow meter would. I never found them to be inaccurate but it was something I hadn't put much thought to prior to installing. Still amazing devices in my opinion and worth every penny
 
jonl21 said:
My Tacs line up with sync gauge but my throttles are at different positions, makes my OCD itch. That's why I'm installing Fox Marine gateways next season so I can see all digital readouts on my Garmin.
Click to expand...
Jon, thanks I have OCD as well. Do you have more information on the Fox Marine gateway? I have 1999 Merc 454's and wonder if they offer the data to the gateway.
 
Strecker25 said:
I've never had a boat where the throttles matched. The DTS boats are probably different, but little nuances like a stretched cable or different routing from one side to the other could affect it.

My sanity check on our 410 is fuel burn. If both engines are taking nearly the same fuel on fill up, I don't worry about it. If one side burns significantly more then it warrants further investigation. That requires separate fuel tanks, obviously, which our 290 didn't have.

Keep in mind the fox gateways are reading injector pulse frequency and the fuel flow the computer is asking for, not actual fuel flow like a flow meter would. I never found them to be inaccurate but it was something I hadn't put much thought to prior to installing. Still amazing devices in my opinion and worth every penny
Click to expand...
thank you Ryan.....
 
Royalboater said:
Jon, thanks I have OCD as well. Do you have more information on the Fox Marine gateway? I have 1999 Merc 454's and wonder if they offer the data to the gateway.
Click to expand...

Yes, they do. The Fox website explains it quite well, but you'll first determine which version of ECM your engines have, and then order the appropriate gateways. For MEFI ECM's that don't include oil pressure data, Fox offers an additional sensor to put that on the network. (I didn't order that and wish I had)

My Garmin units round RPM's to the nearest 50, but I find that to be MUCH more accurate than my tachs have ever been. Their BT app provides exact data to satisfy OCD.
 
Royalboater said:
Jon, thanks I have OCD as well. Do you have more information on the Fox Marine gateway? I have 1999 Merc 454's and wonder if they offer the data to the gateway.
Click to expand...

Pretty much what roller coastr said. Very straight forward, The website lays it all out, and it is sent with the install instructions. Extremally simple setup almost plug and play.
 
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