The Triumph Dolomite Club - Discussion Forum

If the newly installed system appears not to work, first recheck all connections then carry out the following tests. All tests are carried out with the ignition switched on and the centre HT lead removed from the distributor and held approximately 65mm (1/4inch) from an earth point such as the engine, but away from the carburetor region

1. To test the complete system. With the distributor cap removed and out of strong sunlight, a piece of opaque material such as a piece of black card. is passed between the lenses of the optical switch. This should produce a spark from the HT lead to earth

2. To test the power module (and coil) a)unplug the 3-way connector leading to the distributor and connect (by means of a small piece of wire) the blue wire to the black wire leading to the power module. As this connection is made, a spark is produced at the HT lead. If no spark is produced, the power module is suspect. If a weak spark is produced, the coil may be suspect

To test the optical switch The optical switch must be connected to a good power module With a sensitive voltmeter measure the voltage between the blue and black leads When the infra-red beam is not interrupted the voltage is approximately 2.7v. This drops to 1.0v when the beam is interrupted. NB The voltage on the red lead is approximately 7.5v Do not leave the ignition on for more than 15 minutes with the optical switch assembly disconnected

Under no circumstances should: (a)a full positive feed be applied to any connection other than the red positive wire of the power module supplied with a male lucar terminal. (b)The coil terminal be short-circuited or the Brown wire (coil –ve) of the power module be connected to full positive feed. Failure to observe these notes will result in irreversible damage to the power module invalidating the warranty. Suppression can be fitted if necessary between coil positive (switch terminal) and earth, usually 1.5 to 2.0 Mfd

This sounds like an issue i had with my new starter motor when the garage fitted it for me.

It was fine for a while but then the routine for starting the car became turn it over (no spark not even trying to start) release the key and it would start just as you release the key.

The problem was the new starter motor didn't have the wire to supply full battery voltge to the coils whilst cranking like the original starter. (the garage who fitted it should have probably noticed)

I presume as the battery got older the voltge was too low when the starter motor was turning over, but as soon as you relese the key the engine is still turning and the coil gets more voltage and the car starts. (like a mini bump start)

I fitted a relay to cut the power to the electric fan and supply battery voltge to the coil on cranking. Been fine ever since.

If you have the original starter is the wire from it supplying the battery voltage to the coil on cranking?

(Forgot to say i have an 1850 with a lumenition as well)

This sounds like an issue i had with my new starter motor when the garage fitted it for me.

It was fine for a while but then the routine for starting the car became turn it over (no spark not even trying to start) release the key and it would start just as you release the key.

The problem was the new starter motor didn't have the wire to supply full battery voltge to the coils whilst cranking like the original starter. (the garage who fitted it should have probably noticed)

I presume as the battery got older the voltge was too low when the starter motor was turning over, but as soon as you relese the key the engine is still turning and the coil gets more voltage and the car starts. (like a mini bump start)

I fitted a relay to cut the power to the electric fan and supply battery voltge to the coil on cranking. Been fine ever since.

If you have the original starter is the wire from it supplying the battery voltage to the coil on cranking?

(Forgot to say i have an 1850 with a lumenition as well)

You have a ballast system.

A ballast system works by using a 9v or 6V coil which is fed 12v via a ballast resistor. That supply is what you use when you're normally running and not cranking over. When you're cranking you bypass that and the coil gets the full battery voltage. Which is suppose to compensate for voltage drop during cranking.

With no feed from the starter, your coil would only be getting supply via the resistor, which would explain your lack of spark. Unless you had a strong battery.