Just bought a 306 XSi 2ltr twin cam. Pervious owner had removed battery for several months and now turns over but won’t start , is it as simple as resetting ecu?
We're all used to EFI cars starting on the first turn or two, so we rarely experience what happens when they don't (like when they've been sitting for a long time). In my experience many EFI cars are actually very prone to flooding if (for any reason) they don't fire immediately. If you haven't tried already, try holding the accelerator pedal flat to the floor as you turn the key, before you go looking for other issues.
If it still doesn't start, next step is to check that you have power to the coil pack and that all the ignition leads are ok and spark plugs are clean.
Check big red button
Check double relay mounted on the battery box (rear of)
If the relay is dud it wont fire injectors, spark or prime the fuel pump.
Check your getting voltage at the pump with a multi meter. Not sure if the XSI primes when you turn the ign or not? Matt??
Have a look at my thread in the technical section about the 306 cranking but not firing.
I was thinking this too as it sounds like it, symptoms are true to this. Check the RF ring connector in key barrel assembly, clean contacts. RF chip is a piece of graphite in key, don't loose it, its quite small and hard to see.