4 replies to this topic

[hallett]

Hi everyone, I have recently been having an issue where the car will cut out, the Rev counter shoots right around to 8000 and then the car will start firing again and carry on, all of this happens in about a second but it's becoming more frequent, does anyone know what this is? I thought it might be the coil as I believe the coil runs the Rev counter? The idle is also pretty rough but has been for a little while, thanks

Daniel

[KernowCooper]

Usually when the rev counter goes erratic with the engine missing it points to a low tension issue on the ignition circuit, disconnect the rev counter off the coil - terminal and retest the vehicle to see if its inside the rev counter. If its still doing it then check your points/condensor if your not electronic and all the Low Tension Wiring to and from Coil/Distributor.

[hallett]

Ok i will try that later, now I think about it, in the past the Rev counter has stopped working and then started again after about a minute and also when I turn off sometimes the Rev counter jumps to about 3000 before going to 0 but neither of these involved the engine misfiring, would this be a related issue?

[KernowCooper]

Could be disconnect it and road test it and then move onto the other items if required.

[dklawson]

Ok i will try that later, now I think about it, in the past the Rev counter has stopped working and then started again after about a minute and also when I turn off sometimes the Rev counter jumps to about 3000 before going to 0 but neither of these involved the engine misfiring, would this be a related issue?

 

As Dave said, the issues may be (and probably are) related to a problem inside the tach.  As was pointed out, a voltage sensing tach is connected to the coil (-) terminal.  If there is an internal problem with the tachometer and that problem creates an intermitent short to earth of the sense (white/black) wire, the ignition may be disabled.  Basically the tach may be acting like a kill switch if it is shorting the sense wire to earth.