Any Help on a Sun Dual Tachometers

[Lloyd]

Hi Group,

I'm hoping someone on this forum, may help me solve an re-installation, on a boat that I just rewired.

The boat has lower and upper steering stations, each station has a full engine panel for gauges, each station has temp/oil senders. My problem is with the SUN Tachometers, these are early 60's models, there is a control box and were previous wired parallel, which is the way I rewired them, but now the tachs don't read correctly at anything above 900 rpm, but appear to read correct between idle(550) and 900, then above that they top out at 1200 even at wide open throttle.

There are 2 tachs for each engine, each tach has a plus and minus terminal, that goes to a control box (1 for each engine x 2 tachs) Then each control box has an engine ground terminal, a distributor terminal that goes to the neg side of the coil, and terminal marked primary wired to the ignition SW.

The owner said the tachs worked prior. I cannot find any info on the dual tach controller boxes, just the singles. I did find that the single has a mercury battery cell that can't be replaced bc they are no longer manufactured, and an alkaline cell can be jerry rigged to match the voltage of the merc cell.  Could this be the problem???

Or maybe the tachs + - should be wired in series, instead of parallel???

Any thoughts any one???

Thanks,

Lloyd

[hal]

Here is a forum link for the 1.35 battery.

http://www.jalopyjournal.com/forum/showthread.php?t=48022

Which model Sun Tach do you have?