Pontiac Repair: 1993 grand am 2.3 quad4, fuel pressure regulator, vacuum line

Question
engine starts but dies , did run but no power,so i replaced plugs boots and coil cover,need to know if i do a fuel pressure check with just key on and get 42lbs.while pump is cycling then drops to 0 lbs.when cycle quits. didnt know if this is normal

Answer
David,

 Normally the drop in pressure when the pump stops wont cause the type of problem you seem to have, unless the fuel is leaking in the fuel pressure regulator down the vacuum line into the intake manifold. The regulator is on the fuel rail and has a vacuum line connected to it. Remove the vacuum line and look for gas in the line. You could cycle the pump on and see if it comes out of the regulator end. I would guess odds are its not but it could be. In this case the engine would be over fueling and a new regulator would be needed. If not, the likely problem with the pressure is the check valve in the fuel pump and that's there to mainly there to combat vapor lock and that only happens when the engine is hot and shut down and restarted within an hour or so.
  Assuming this is not a problem I would look first at the check engine light with the ignition on, it should come on If not its likely a computer problem or the power feed to the computer. If that's OK then I would check for a injector pulse when the engine is being cranked. You can use a standard test light connected to each terminal of the wiring harness with the connector disconnected. Crank the engine and look for the light to blink. If not check the power feed to the injectors normally under the hood. If your not getting a light I would first ground the test light and turn on the ignition and probe each of the two injector terminals. One should have voltage and light the light. Make sure you test the test light on the battery to insure operation and a good ground while testing. If you have power there I would double check the first test on the injector connector. If it has pules or not I would then check spark. You could do it first if its easier for you. If you have spark or injector pulse you know the crank sensor is working. If your crank sensor is bad you wont have spark or injector pulse. This can be confusing and a bit out of order but you need spark and pulse along with 35 to 42 pounds of fuel pressure to get the engine to run along with a check engine light. Some Q-4 engines did have a problem with there oil pump via the pressure relief valve. This would when cold cause such high oil pressure that the lifters would hold the valves open and thus the engine would crank real free and with no compression it would not start. The easiest way to check this is the most dangerous as well. Yes drain the oil and remove the filter. Crank the engine and if it fires even a bit shut it down fast. Do it quick and you have the answer. You could connect a pressure gage and I think I have seen over 100 psi cranking or so. This is not what you want to see and would need a new pump/pressure regulator as I didn't do this I can't say if the parts are sold separate. Again check the check engine light, the spark and the pulse. One surely will not be there. John