Originally Posted by Pleiades

Sounds to me like it may well be that the injector wiring has an intermittent short or open circuit. It is a reasonably well documented problem on the XTZ.

Where the spur for the injector branches off the main loom it is unsheathed and is tight up against the right hand frame rail. Eventually is can rub through and cause the injector to short to earth causing non-starting, miss-fires etc. When it's shorted the engine trouble light will be on, when its OK it won't.

Take a look at this photo. The yellow ring shows the problem area and you can see I've put a foam pad between the wires and frame to prevent the problem happening.



If it is this problem, then you'll have to repair the damaged wires and pack out the loom with something at this point to prevent it going again.