Hello mate!

Right, just been doing some hardcore wire tracing on the diagrams. Firstly:DazC I know the relay you are on about now, kind of left my brain cos as i haven't got one on mine, as i have series 2 management wiring. The said relay is the Fuel Injection MODULE Relay, does everything that the later S2's KE protection module does, and also switches the supply rather than have the feed straight off the ignition switch (same end result),

You said about it having some form of diode...Correct! Its got a Zener protection diode which protects the module from over voltage. Can't see any glass fuse on the internal diagram of the relay but i you seem pretty clued up and it would make sense to have one.

The fuel injection fuse (Fuse R1), supplies the permenantly live feed straight from the Busbar to both the Fuel Pump Relay, aswell as the Fuel Injection Module Relay, and again as DazC said, if the fuel pump is running, then the fuse is ok.

Now, the bit im not convinced about is that its a wiring fault or electrical fault, because as vroooom ptssssh says, once he eventually gets the thing running, and up to temperature its fine. Now i know if there was no feed getting to the KE Jetronic ECU, the car won't cold start well, but it also wouldn't run when well hot, vroooom ptssssh says when its hot the car drives and boosts perfectly.

Cold start enrichment, and full load enrichment (on boost), are controlled solely by the Hydro electric Pressure Actuator, which in turn is controlled by the KE Jetronic ECU.

Its certainly worth a check inside the relay as DazC said, there is a glass fuse in it, but im not convinced thats the problem.

Just for reference aswell while im here, im sure this will help someone else:

The series 1 loom (the wiring from both the ECU's to all the relevant ancilliares) is identical to a series 2 loom, with the following exceptions:

Series 2's had a second CTS (Coolant Temperature Sender) fitted, which gave the IGNITION Module Coolant temperature info (One pin of the sensor connected to pin 8, the other to Negative/Earth)

Series 2's had the Knock Sensor added (One pin connected to Pin 10 of the IGNITION Module, the other connected to Pin 9)

The wiring for both the Series 1 & 2 was identical, (Series 1 loom being minus the 2nd Coolant Sensor, and Knock Sensor, and having a few colour variations) with the following 2 variations (neither of which change functionality)

The Negative/Earth connection of the TPS (Throttle Position Sensor) on the Series 1 loom is connected to Negative/Earth via Pin 6 of the Bosch KE Jetronic ECU, where as the Series 2 loom has the connection as part of a common Negative/Earth point.

The Series 2 loom has additional screening built into the loom (more than likely as an improvement against HT interference)

This means a later ECU can be used on an early car, just aswell as an early ECU can be used on a later car (but the 2nd CTS and Knock Sensor are rendered useless in this combination)

And finally, the loom in its entireity, has only a mere few connections into the cars wiring which is standard through the range:

3 x Black/Yellow wires (4 wires on a series 1, the fourth being to the Series 1 Fuel Pump Relay which was unique), connected to the stater motor cranking wire, providing a feed while cranking for:

Cold Start Valve
Thermo Time Switch
Bosch KE Jetronic Relay (Pin 24)

2 x Black Wires, connected to the main Ignition Relay to supply a switched feed to the coil, and a switched feed to the IGNITION Module.

1 x Black/Green wire (Red on a Series 1), the main OVER VOLTAGE PROTECTED FEED to the Bosch KE Jetronic ECU.

1 x Green wire, from the negative side of the coil, connected to both the Fuel Pump Relay and the rev counter.