Synch gauge inop at higher RPMs??

***EDIT: Ooops... there is an electrical forum. Should I delete this and repost there?

I recently installed a new Faria Synch Gauge. If I am idling, it is nearly impossible to keep the gauge showing synched, but it seems to work properly. If port is at 800 and starboard at 1000, it points toward port; and vise-versa. Seems to swing appropriately and work fine at lower RPMs.

As soon as we throttle up, however, it starts to lean to the left (port supposedly slow) and basically stick there. I can run port up well beyond starboard (3k/2k), and the gauge still says port is slow. I can keep port at 3000 and pull starboard completely offline and the gauge still does not move; but as soon as I pull both of the engines down below ~2k, the gauge seems to "unstick" and float freely, and accordingly with the engines.

Any thoughts? Seen this? The tachs move, but the synch freezes... ?? Bad synch gauge? I don't want to return it and have the replacement do the same thing, you know?

Already looked at Faria's FAQ and such. Verified the selector position on the back of the gauge, etc..

I have read others on here mentioning ignition coils should be on relays. Ours are not. They are powered directly off the igntion switch. Could it be a current draw issue? Too much power being sucked through a 30-foot 10ga wire?

Any ideas are appreciated. Thanks in advance!

I just installed a Faria gauge myself last week. Mine works, but I agree it's really sensitive especially at lower RPM's. At cruise it seems to work ok.

I replaced an old Guest unit which had LEDS and used the same wiring.

I'm not positive but it sounds like you have a bad gauge. You could try reversing the port/starboard wires and see if the problem moves.

Bob

I'd call them and speak with their tech support group. haven't done it lately but was very happy with the responses when I have called.

I'd suspect the comparator in the gauge has an issue - bad solder joint, wrong component, etc. The basic design concept for the sync gauge is straightforward and simple...everybody seems to want to put their own spin on it so each brand has their quirks. When the module on my old quicksilver sync gauge went, I just built a new one - not pretty but very effective.

Faria's support said to disconnect the signal wires from the tachs, but leave the wires connected to the synch gauge. If the problem remains, send it in for replacement. I have no idea how old the tachs on the boat are, but after some tweaking with an allen wrench, they are pretty accurate now. Could an old/bad tach cause the synch to not work? Seems strange, but I will try it.

depends.

old tach, not likely.

Bad tach - depends upon the failure mode and the details of Faria's interface design on the sync gauge. Most sense the pulse frequency (from the coil firing) and convert it to a voltage. The voltages produced from each engine are set to have opposite polarity. These are applied to a differential volt meter. if the bad tach alters the pulse shape such that the voltage produced at the interface of the sync gauge is impacted then, Yes, it will effect the sync gauge operation.