I have a 1995 Pontiac Grand Am with the Quad 4 engine. It will run for 10 to 20 seconds before it stops. It seems like it's not firing. There are no codes in the computer and it has 40psi fuel pressure. We tried a fuel regulator, cam sensor, coil pack and an ignition module from another running 2.3-liter. And we also changed the crank sensor. Do you have any suggestions?
You should be checking for workable fuel, spark and compression before swapping any parts. In the meantime, your description of starting up and shutting off sounds similar to the operation of an antitheft system.
When improper use of the ignition is detected, the system will allow the engine to start up, but then disable the electrical pulses to the fuel injectors and shut it down. If there's a security light on the instrument panel, your Grand Am may be equipped with a system which warrants further investigation.
Also, GM's Quad 4 2.3-liter DOHC inline four cylinder engines began production in the late 80's, and didn't undergo a complete redo until the '96 model year. So I'll point you in the direction of some common Quad 4 ailments which may still have been relevant in '95.
First and foremost is the blown head gasket, which was not only common but inevitable on early production engines. Next is an oxygen sensor failure which can produce deplorable drivability conditions, without setting a trouble code, due to coolant contamination from the exhaust due to the blown head gasket.
The coil pack consists of two ignition coils located within an ignition housing. An insulation breakdown of the housing also caused misfires and near shutdowns. Get it to a technician before replacing additional parts.