No spark

[Sandboy]

Need help trying to diagnose lack of spark, on last run out car died a few times, couldn't hear pump prime so changed fuel pump relay and car started again and got me home but then wouldn't start at weekend. Again couldn't hear pump prime so replaced pump relay again but no joy, shorted relay and pump ran with plenty fuel flow at rail although haven't checked with pressure gauge, so began to think fuelling a red herring, although just occurred to me that perhaps should check whether injectors firing. Moved onto spark next but not getting one and so wondering what should check next, crank sensor or coil, ecu or something else? Trying to be methodical but limited experience of fault diagnosis so would really appreciate some pointers on what to check, how to test and best sequence. Got a sprint at Three Sisters at weekend and really don't want to miss so any advice gratefully received. Engine is xe with omex ecu.

[ECR]

From Dave Andrews (I think)

 

What to check if you have no Spark at the Plugs

Although there are many sensors that can fail, there are very few that will stop the spark, most will simply cause incorrect adjustments to the fuelling or timing.

If you are getting no spark then either you have a very low battery, a wiring fault, a faulty CPS or a faulty ECU .

 

A faulty TPS or MAP sensor will not stop the spark, in fact the ECU will still fire the coils with no TPS connected or with a bad MAP signal.

 

[Sandboy]

Thanks ECR, battery and wiring ok, not condeming ecu until eliminated everything else, CPS gives 538 ohms but don't know if that is good or bad, think will open another thread on testing CPS.