My car will not start. It was fine in the morning going to work, but to come home it would turn over but not start at all. AA sprayed engine cleaner into it which made it start, but then the engine cut again at idle. I got towed to my local garage, but they cannot find the fault. They suspect it's an electrical problem.

There is power at the fuel pump, but apparently no power at the glow plug. Any ideas what this could be?