2003 Streetka Deluxe 1600 duratec engine. A few months ago first thing in the morning it started to start on two cylinders (after pumping up the petrol) then picked up the others and was OK for the rest of the day.

Just before Christmas it fired on one a few times and then nothing.     New battery, new plugs, new air filters, fresh petrol.   Spins over briskly.  Plugs are wet so petrol getting through.  Timing light picks up a few sparks on 2 and 3, none on 4 but most on 1.   Testing each plug by sight shows a good spark.   "New" coil pack no different.  Disconnected battery for a day, no different.    There are no codes!   

If it were one of my vintage cars I would just drag it down the road and it would go but this one baffles me.   Fuel injectors perhaps?   

Try a another crank sensor, should be able to get a cheap one off ebay. Unless you have a ocilliscope and can check the waveform first before purchasing another sensor 

Back to first principles.   If there is compression and ignition there must not be fuel.    Change fuel filter, switch on, wait a bit..

Churn

Churn churn churn

Cough, churn cough

Cough cough sputter sputter vroooom with much white "smoke".  Cleared that by trip round the block, listening to tickover and there is a whistle, traced to air leak in the camcase breather pipe.  Could this be the underlying problem, weakening the mixture for starting?    Anyway, we seem to be back in business, having sealed the leak.