zimmf3

I was driving my 72 tr6. The car I thought stalled. No spark. Changed the cap rotor points condenser. Still no spark. Tested the coil very weak spark. Changed the coil still weak. Changed the ignition switch. Still weak. The motor cranks over as it should. What is going on. I need help.

zimmf3 said:

I was driving my 72 tr6. The car I thought stalled. No spark. Changed the cap rotor points condenser. Still no spark. Tested the coil very weak spark. Changed the coil still weak. Changed the ignition switch. Still weak. The motor cranks over as it should. What is going on. I need help.

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somehow you have posted this in the software section and not the Triumph section - can you repost there? (or perhaps a moderator can move this)

OTOH have you changed plug wires?

Is the alternator charging? this would explain the stalling.

Zimmy please post your Triumph questions in our Triump forum.

PS: I’m moving this post there now.

How did you test the coil.... when off the car or still connected?
And tested the replacement coil on the car?
Fitted a new correct condensor?

Have you checked the rotor and carbon brush in the distributer cap?

David

The motor cranks over as it should
That's because the starter circuit is independent of the ignition circuit. Don't let that concern you.

My guess is that you have an intermittent loss of voltage to the coil. The spade connector on the coil is where I'd look first.

The TR6 may have a ballast resistor or a resistor wire. Check your diagram. https://www.advanceautowire.com/tr2506.pdf If so, you can check it with an Ohm meter or simply temporarily bypass it with a jumper.
Tom

Randomly replacing parts isn't a good way to fix electrical problems. Better to troubleshoot it methodically.

Start by measuring the voltages at the powered side (i.e., not the distributor side) of the coil with the ignition on. If you don't see battery voltage, work back toward the switch and find where you are losing the voltage. That will tell you where the bad part or connection is.

If that's OK, disconnect the wire from the coil to the distributor and put an ohmmeter on the distributor connection and ground. Turn the engine over, and you should see the resistance vary from a short to an open circuit as you crank. A powered test lamp works OK for this, too. If this doesn't check out, the points are shorted somehow, probably installed wrong or a conductor is touching something it shouldn't.

Use the ohmmeter to check the coil for an open circuit. You should see a few ohms, at least.

If all these check out, the primary circuit is OK. The only remaining possibility is a bad capacitor--new ones are garbage--and that's hard to test.

To check the secondary circuit, hold the high-voltage cable from the coil center terminal to ground and see if you get a good spark while cranking. If not, and the primary checked out OK, probably a bad coil or wire. If so, do the same with individual plug wires. If nothing at that point, probably something is bad in the cap or rotor.

High-voltage problems can be as simple as a wire that isn't pushed all the way into the cap or coil connection. Don't discount simple causes.

Are you using points or something electronic (e.g. Pertronix)?

If points, check the gap. If Pertronix... well, I dunno.

Geo Hahn said:

Are you using points or something electronic (e.g. Pertronix)?

If points, check the gap. If Pertronix... well, I dunno.

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Agreed! Those Pertronix ignitions can fail in some very funny ways. I know...

Sarastro said:

Start by measuring the voltages at the powered side (i.e., not the distributor side) of the coil with the ignition on. If you don't see battery voltage, work back toward the switch and find where you are losing the voltage. That will tell you where the bad part or connection is.

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Except if this TR6 does have an external resistor, and I think it does, you should get less than battery voltage (6-8 volts) at the ignition switch side "+" of the coil. This would be perfectly normal.