Chevrolet Repair: 93 chev. lumina 3.1 engine, oil pressure switch, crank sensor

Question
when you go to start the engine the engine will start but it dies in a few seconds and to get it to do it again you have to turn key off and try to start again we have changed the crank sensor and that is all it is showing no codes and the fuel pressure is good

Answer
Hello Gary,
The fuel pressure is good, but is it staying up at full pressure till after the engine dies?
And are you checking the pressure at the fuel rail?
I am wondering if it is running on the initial three seconds of fuel pump, then the relay dropping out.

Critical question, though is if the pressure drops before the engine dies.
There is an oil pressure switch that supplies power to the fuel pump after the oil pressure builds up, but you may be in the area between.

Now, since you have checked the pressure, even if it stays up, there could be an injector signal loss...and it could be a spark problem, but checking to see if spark is present AFTER it quits running may be tricky. But if it does it time after time, I would connect a spare spark plug to one of the wires, and ground it, and see if spark continues after it dies...just a couple hits. But that will help you decide weather to concentrate on fuel or spark.

Either one could be caused by the ECM, but I am sure not a proponent of just buying parts till one fixex it, because if you have an electronic problem that is because a short, for example, ruined a computer, and you replace the computer without finding and repairing the orriginal cause, then the same fate can happen to the brand new computer, and you won't even know it.

So getting a shop manual with troubleshooting chart may be necessary.

Have you tried a little starting fluid to see if that will keep it running?

Van