Jaguar Repair: daimler double six, fuel pressure gauge, bright sun light

Question
My 1978 v12 starts ok but when it gets up to temp stops, it will not restart until totally cold again. Tryed new coil and have checked spark it is firing so assume injection system, Lucas type2 ? Fuel pump runs and system pressurizes when ignition is switched.Help please.

Answer
Hi Phil,
I am guessing that the V-12 Daimler is the Jag engine.
For the engine (or any engine) to stop when hot, it must be loosing either fire or fuel so the first step is to determine which is lost.
Very rare for an engine to loose compression hot and regain it cooled down.

Ignition is fairly easy to test with a timing light or just a spare spark plug. To test for injection pulse you can get a "Noid" light from most any auto parts store. (not expensive) You need the one for Bosch or Lucas. That will test for injection pulse. You also need to monitor the fuel pressure. Some of the fuel injection system gauge sets are a little pricey but you can just purchase an industrial gauge and a few brass fittings and some fuel hose to do the job. That is what I used for years before I got a professional set. Probably operates in the 30+ PSI range.

Keep in mind that you should have everything connected up and be monitoring while the engine is getting warmed up, so you can see which is failing. The Noid light is the only thing you will need to plug in after it quits. Put a timing light on and tape the trigger down and put the fuel pressure gauge in a "T" so you can monitor pressure at the time of failure. I have many times in the dealership had to run the timing light out from under the hood and put it under a wiper arm and tape a piece of cardboard over the end of the timing light on the windshield so I could see the flash in the bright sun light when driving the car and at the same time I had a fuel pressure gauge under the other wiper arm so I could see which failed when driving as some failures were only a few seconds and only intermittent. (Very difficult to find these types of failures any other way)

With no storage of codes on intermittent failures on older cars you have to set up your own monitoring system.
Howard