Ptero Posted July 9, 2011 Share Posted July 9, 2011 A few details on the car. 1973 240z /w electronic ignition. Using ignition module E12-80. Exactly as the title says. When cranking the car, the tach will bounce a bit but then drops back down to zero once the car has started. When driving the tach stays at zero. Not too sure if it worked before as I'm the new owner and don't know the history of the electronic ignition change. Today the tach slowly crawled up to 8k and stayed there until I turned the car off. I did however read that this happens when it's hot outside and today was one of those days. So that one makes sense (to an extent). I searched but didn't find another issue like this one. Is my tach fubar'd or do I still have a hope of getting this thing working? What I found on the tach going up due to hot weather. The tach in 240zs are known to malfunction when it gets hot (95+) outside. I believe it is the resistance (?) loop on the back of the tach which causes the problem. Under normal operation, this loop heats up due to the current passing through it. When it gets hot outside, the heat is unable to dissipate as well and the tach starts to creep up over time. Eventually it will just peg at redline. Quote Link to comment Share on other sites More sharing options...
DatsunZman04 Posted July 10, 2011 Share Posted July 10, 2011 240z Tachs are know to be sketchy at hi temps and poorley unacurate. Your early 240's tach are not compatable with a eltronic ignition (pertronix).They require a resitor soldered in to make them compatable. You can always hook up a temp rpm tach to make sure everythings working correctly. I would check all wires, then I would put the original rotor and points in just to see if it makes a differance (if available). Just my 2 cents, I know this really doesnt help you but good luck. Quote Link to comment Share on other sites More sharing options...
Swifty Posted April 17, 2012 Share Posted April 17, 2012 This thread has been dead for about a year now. Sorry for bringing it back up. But im having a slightly similar problem, and I couldnt find anything in the search. My speedo and Volt meter works fine "if you over look the fact that my speedo fluctuates slightly" But everything else doesn't work all the time. If I go over a bump all the gauges will come to life, fuel level, Engine temp, oil pressure and tach. Then if I hit another bump, they all die out. Im sure its a ground issue, but since I dont have a wiring diagram, I have no idea where to start. Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 17, 2012 Share Posted April 17, 2012 http://atlanticz.ca/zclub/techtips/electrical.htm http://xenons30.com/reference.html http://xenons130.com/reference.html Quote Link to comment Share on other sites More sharing options...
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