Type 4 ignition issues Options

[VaccaRabite]

This is for my 1972 bus, but it’s very similar to a carbed 914. I am in a no start situation.

1.7 Type4 engine.
123Ignition dizzy (new)
New 12v coil - 3.6 ohm

Voltage from terminal 15 (+) on coil to ground is ~9 volts.
Voltage from terminal 1 (-) on coil to ground is 12.6 volts (battery voltage)

If I run a jumper from 15 to ground I get 12.6 volts - but still no start. So- I’m getting voltage drop somewhere.

Plug wires are spiral wound wires. I tested the resistance of the center wire (dizzy to coil) and it was 767 ohms. Wire is about a foot long, so that is in spec.

The green light in the 123Ignition turns on if I spin the body. So not only am I pretty sure the unit is getting power, but I’m also pretty sure the timing is close enough that I should get it to start.

123Ignition is wired correctly. Red to 15, black to 1 on coil.
Fuel pump is also running through the coil and it runs solidly on key on, and key off but jumper end from battery + to post 15 on the coil.

I have tried removing the tach and fuel pump wires - no help.

I don’t think this is a 123Ignition problem. I think this is a bus wiring problem.

History - bus was running AWESOME. Went for a 120 mile drive, but before I got out of my neighborhood I started missing bad and limped home a couple miles on 2-3 cylinders. This was back in December. I tested the coil and it was reading 2ohms across the primaries so I figured I had blown up my points (points generally want 3+ ohms). I now think my points were likely fine, and I am dealing with a bad wire or a bad ground somewhere.

Okay brain trust. What you got?

Thanks
Zach

[Superhawk996]

Confused. You mention 123 dizzy but then talk about points. I’m gonna assume the points you were talking about were before the 123 dizzy install.

This is also confusing:

“Voltage from terminal 15 (+) on coil to ground is ~9 volts.
Voltage from terminal 1 (-) on coil to ground is 12.6 volts (battery voltage)”

Terminal 15 is supposed to be 12v. (You say you have 9v)

Terminal 1 should be connected to 123 dizzy black wire (you say it is) and is a switched ground provided from the dizzy . Ie. The 123 dizzy mimics points opening and closing as it rotates providing a pulsed ground. This means terminal one should alternate between 12v and ground depending on the state of the 123 dizzy. As it sits and as described, it sounds like the dizzy is “open” and isn’t actively sourcing a ground which is what I’d expect with the dizzy static (engine not running) - and you would measure 12v on terminal 1 in this condition (assuming you have 12v on terminal 15 - but . . . You say you have 9v) so in theory we would expect to see 9v not the 12.6v you are saying your measuring on terminal 1).

Something ain’t right.

“ If I run a jumper from 15 to ground I get 12.6 volts - but still no start.”.
I have no idea what you’re saying or what you mean by running a jumper. A jumper from terminal 15 to ground would be a short circuit from a 12v supply (terminal 15) and ground. A short like that should make sparks, and would melt the jumper wire or blow fuses. [edit: when you say ground are are you referring to the coil negative (terminal 1) or actual chassis ground?]

Again, something ain’t right.

So I’m either completely misunderstanding or there is something very wrong with the way it’s wired.

Without waiting for your reply, I’d disconnect terminal 1 - the 123 dizzy. What do you get on terminal 15? Should be 12v.

[Superhawk996]

I’m also confused about the fuel pump.

You say you removed the pump wires and tach wires from the coil but it made no difference. But then how were you powering the fuel pump?

And when the fuel pump was removed from the coil were you still measuring 9v on coil terminal 15?

[Superhawk996]

Let’s just put the 123 dizzy schematic here for clarity.


For clarity I’m going to assume the 123 dizzy you have isn’t the POS option and doesn’t even have the blue wire. Similarly assuming that since your carbed, there are no wires for fuel injection trigger points.