iv had simular probs with my 19j i would think you need to test the heater plugs first i had the same problem for 4 years iv changed the starter, battery, heater plugs, injectors ,pistons and just about everything you can think ov even the injection pump . i was just about to give up when i found a thread about a 19j cambelt timing position everybody told me the timing point on the injection pump was the dot like it shows in the haynes but it turnes out thats the 12j engine the 19j is on the f mark next to it . i did this and it starts fine now with no white smoke at all i just had to move the pump around by a few milimeters . if all als fails try this it worked for me . good luck