Author Topic: new tach causing car to not to start  (Read 443 times)

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Offline iflyn95bt

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new tach causing car to not to start
« on: July 12, 2017, 02:09:42 PM »
Have a 1978 Trans Am with 403 engine and rally cluster.  Installed a new tach (old one did not work).  Car starts fine when the 2 pin connector not attached to the tach (rest of the cluster plugged in), but when i connect the tach i cannot get the car to start.  I have changed the PU coil (tested bad), the HEI module, and the ignition coil.  Have double/triple checked to ensure installed correctly, and still cannot get car to start with tach connector attached.  i have also tested the output from the connector with the car running and the voltage increases as you would expect with the increase in RPM.  Suggestions on where to look now?

Offline Angelo

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Re: new tach causing car to not to start
« Reply #1 on: August 07, 2017, 06:48:44 PM »
HEI distributor? The tach should only have one wire, the other terminal on the cap is for the ignition itself, if that is disconnected I don't know how it would ever start.
81' ex-Turbo Trans Am - Resto-mod

Offline TAKID455

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Re: new tach causing car to not to start
« Reply #2 on: September 09, 2017, 09:22:55 AM »
Check ground to the white wire. If that circuit is grounded/ shorted, it will kill the output of the ign moldue.
2nd Gen Engineering
Specializing in Suspension and Driveline Performance Engineering
Custom/ Racing/ Restorations