2F TBI, Ignition Problem. (1 Viewer)

[flozano]

Hello

I have a toyota Land Cruiser with 2F engine (I6) and I'm installing a 4.3
Chevy TBI.
My engine run, but my tach is crazy on high RPM (2500 RPM) and some times at
IDLE, and at the same time my ignition don't fire when the tach is crazy.
My ignition module is new, I use an 1227747 ECM, and a custom chip. I have
a GM HEI Dist, and the ignition module is installed outside of the
distributor.
When I disconect the timing connector, My tach work grat and my ignition
work witout fails.
any idea?
may be I have problems with my custon chip or my coil?

 

[Pin_Head]

I presume that the tach is wired to the - side of the coil.

Sounds like an impedance mismatch between the ignition module, the ECU and the tach. Doesn't the ignitor or ECU have a separate tach connection wire? If so, get a tach that works with EFI ignitions and wire it up to the ECU or ignitor and not the coil.