twin 1997 225 tach problems

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i have 1997 225 twin engines replaced with new tach's with system check lights in tach;s ( 8 pin conecter) bolth tach's read the same with one engine running and only the key on on the other and vice versa tach's always sincronized with each other, the pulse switch is set to 6 is this correct also they jump around when running at fast speed ( 3500 rpm)

Re: twin 1997 225 tach problems

Miswired.

Re: twin 1997 225 tach problems

i cant miswire 2 wires, purple and gray,.??

Re: twin 1997 225 tach problems

Magic, then.

Re: twin 1997 225 tach problems

unplug all purple and gray wires on bolth tachs ,still working, apparently through 8 pin connector still working together quite the magic!

Re: twin 1997 225 tach problems

Something clearly is miswired or shorted. I have SystemCheck gauges w/o tach on my E-Tecs, so I can't help with the tach feature. You need to look an OEM shop manual which gives a bunch of SystemCheck gauge tests and shows the correct wiring. If the gauges have been screwed up since installation, wiring is where I'd spend my time. The tach feature only needs black, purple, and grey ... the grey and purple must come from the correct engine, so I would start by tracing them from the gauge to the motor for each.

I am assuming each engine has an 8 pin connector associated with it, since that is the total number of possible SystemCheck gauge connections. Somehow, you have the tach connections for both engines tied together (probably near the gauge).

Re: twin 1997 225 tach problems

wierd thing is tachh
s are working through the eight pin connecter ,with no other wire connected therfore ,where to start?

Re: twin 1997 225 tach problems

Disconnect both connectors, then connect one at a time and see what you get. Clearly, wire from one connector is connected to the other. Also, you should check the resistance (not running of course) between the grey from one connector to the other. Should be no connection or infinity.

Re: twin 1997 225 tach problems

The wiring on that motor is designed to allow you to use any standard tach via the grey, purple and black wires connected to the brass screws on the back of the tach. If you want to use a System Check Tach, only connect the 8 pin connector. The rest are unneeded. I think that is the problem.