Toyota Repair: Possible fuel pump problem, camshaft position sensor, fuel pressure regulator

Question
Ted,
I am working on a friends 2000 Lexus ES300. V6 engine, auto trans. The car has recently started running rough. Now it has quit all together. The engine cranks over but will not start. I don't know if is fuel or ignition. The fuel filter has been replaced.
I am trying to figure out if it is a pump problem, a regulator problem, ignition issue or that the camshaft position sensor could cause the trouble as this is supposed to send a pulsing signal to the PCM which controls grounding of the fuel pump.
1. Should the pump shut off once it has reached full pressure? The manual says the pump should deliver 45-55 psi.
2. There is also a fuel pressure regulator as part of the pump. How do you trouble shoot a regulator problem?
3. Since there is a coil for each spark plug is there a special procedure for checking to see if the plugs are firing?
Both the pump and the regulator are over $125 each so I don't want to have to replace anything more than is necessary to fix the problem.
I have trouble shot the EFI fuses and the EFI relays ( There are 2 in series) both relays pickup and the fuel pump runs "constantly".
Thank you for any assistance that you can provide.
Pete Davies

Answer
First lets find out if there is ignition to the coils to fire the spark plugs, remove one of the spark plugs, pull out the EFI relay to shut the feul pressure off to keep the engine from starting, put the spark plug into the end of the coil and ground the body of the spark plug, crank the engine and see if the spark jumps across the electrodes. Do you have access to a trouble code reader?