Hi all
Onto the next part of my restoration and I've hit another snag.
The ute runs and drives well as standard (no tacho)
But when I add the tacho I have ( which is from a 1200 coupe) the engine will idle okay but on acceleration will miss fire and splutter badly.
I have wired the tacho by simply running the induction loop between the negative of the coil.
I can't understand why this would be happening because the wire is continuous ( as it's an induction loop)
Any ideas?

This may help and check all connections and wire conditions

Early Tacho in Newer Truck

If the newer truck doesn't have a dash harness LOOP, you can:

Find the BW wire in the dash, cut it, and connect to the tacho loop
or

Run new wires from coil back into the cabin and connect to tachometer. Discussion follows.
Instead of this normal wiring:

IGN+ --------------ballast--|+ coil

START ----------------------|
Remove the BW wire from the Ballast Resistor, and connect to new tacho wires:


tacho ==========|-|
IGN+ -----------| |ballast--|coil +
START ----------------------|
Which BW wire on the Ballast Resistor to remove? The problem is the Resistor has two BW wires. They are all BW!


IGN+|BW-----------BW<ballast>BW--|+ coil
START|BW---------------------BW--|
You can test this by removing all wires from the resistor, turning key to ON, then test which BW wire has 12V. That's the one to remove and tie into the tachometer