Been having a few problems starting my 52 reg 172 Cup lately. Starts up on second attempt though. Done some research on other posts and TDC sensor seams favourite. One thing I've noticed which is strange though is - When I put the key into the ignition for the first time and turn it so all the the ignition lights come on I can't hear the fuel pump priming up, if i then turn the key back to the 'accessory on' position and turn the ignition back on again the fuel pump primes. Is this normal? or can anyone try this on theirs for me as it could be contributing to my starting problem..Any help appreciated..cheers