Cadillac Repair: fuel pump, control panel buttons, cadillac sedan deville

Question
My friend just put a water pump on my 91 Cadillac Sedan Deville .  He went to start it up and now it won't stay running.  It will start but not stay on.  He thinks that it may be the fuel pump.  What do you think?

Answer
look for disconnected wires in the area where he was working.

Does the oil pressure light illuminate when you turn the ignition key to the ON position ONLY without trying to start the engine ?.

Do you know how to check for COMPUTER FAULT CODES via the CLIMATE CONTROL PANEL buttons ?.