Hi .....Got a strange one when trying to start the car {c20xe} the  ignition  is on turn the key hear a click 3 second delay it starts fine happends like 1 in 10 times .. parts changed Battery( 1 year old} starter motor  ignition  switch battery terminals cleaned all the earth points i could find battery off 12.35 v running 14.86v any help id be grateful of.

There is know relays in the starting system

Fitted a new gm  fuel relay last year know  immoberliser on mine ...yeah could be  Solonoid ive put a brand new battery on it see how that goes

Ive checked all the earths connections and contacts alternator is fine ....it was still doing it after i changed the starter motor ....a delay when you turn the key keep it turned for 3 sec and it fires up ......

3s sounds like a fuelling issue - either the pump not priming (if it’s a model that should) or the non return valve has failed

Haynes manual page 12.30 C20XE Motronic M2.5 The relay referred to is K68 a twin coil relay 6 pins at track 296
location? either relay box in engine compartment? or next to ECU drivers kick panel?

This is a quote from a pdf named "Bosch Motronic 2.5 Copyright Equiptech"
 
The Motronic electrical system is controlled by a single system relay with dual contacts. A permanent voltage supply is made to
relay terminals 30 and 86 from the battery positive terminal. When the ignition is switched on, the ECU earths terminal 85
through ECU terminal number 36 which energises the first relay winding. This causes the first relay contacts to close and
terminal 30 is connected to the output circuit at terminal 87. A voltage supply is thus output at terminal 87. Terminal 87 supplies
voltage to the injectors, ECU terminal 37, ISCV and the FTVV when fitted. In addition voltage is supplied to the second relay
contact.
When the ignition is switched on. the ECU briefly earths relay contact 85b at ECU terminal 3. This energises the second relay
winding, which closes the second relay contact and connects voltage from terminal 30 to terminal 87b, thereby providing voltage
to the fuel pump circuit. After approximately one second, the ECU opens the circuit and the pump stops. This brief running of the
fuel pump allows pressure to build within the fuel pressure lines, and provides for an easier start.
The second circuit will then remain open until the engine is cranked or run. Once the ECU receives a speed signal from the CAS,
the second winding will again be energised by the ECU, and the fuel pump will run until the engine is stopped.

Immobiliser Relay Haynes Manual page 12.28 Relay K3 track 109
 Location= Item 11 page 12.19

Hi rocket.

Your determination to solve your Cali problems is admirable........Repairi ng your car yourself as I do is very cost effective and finding an elusive

Problem and fixing it is so satisfying.  .......When I have exhausted so many avenues I resort to calling a Mobile car tuner to whack her on the diagnostic computer so all starting and running parameters are shown in real time.  Ok it will cost around £40.00 but hire a good one and they

Have a wealth of knowledge and experience.......which will make the session very educational and they can do any needed tweeks or advise you what needs to be done.

You have done well so far.....and even if you have not yet cracked it......the parts you have replaced  thus far has given your car added longevity.
They should be able to trace the problems........and get your Cali running sweet.
Good luck.