Turn key, wait 2 mins for fuel pump, then start

I have a 1996 Lumina 3.1. For the last few years, every now and then I would turn on the key, all electrical systems, lights, windows, radio, etc. would work but it wouldn't turn over. If I waited about 4 minutes it would start perfectly and it wouldn't happen again for up to a month. Last week it did it and after I waited and tried it again it turned over once then everything went dead. A mechanic (friend) installed a new battery and it started. He took it to his shop and installed a new computer. Everything read fine, but now when you turn on the key it will turn over fine but not start. Leave the key on and wait about 2 minutes till you hear the fuel pump start and the engine will start fine. If you stop for a few minutes it will start but if you stop for more than 5 or 10 minutes you have to wait for the fuel pump to come on again. He is stumped

Just throwing out a guess here, but with all the ignition switch issues from that era of GM cars it might not hurt to try.

Just throwing out a guess here, but with all the ignition switch issues from that era of GM cars it might not hurt to try.

I think he checked the switch rather thoroughly. He took all that apart and checked it.

So...you have multiple problems?

Sometimes the engine will not crank, now it cranks but doesn't start because the fuel pump isn't working. Is that right?

Sounds to me like you need standard diagnostic procedures for both the starter motor and the fuel pump.

Was the vehicle scanned for theft deterrent codes?

Bad battery was probably why it wouldn't crank before......

So now, it cranks but doesn't start sometimes? Was fuel pressure ever checked when it wouldn't start?

When it won't start, keep a can of carb cleaner handy.....spray into the intake and see if the car starts.....if it does and then dies unless you keep spraying, then it is a fuel delivery problem...either the injectors are not firing or the fuel pressure is low.....could have a bad fuel pump relay, try swapping the relay with another in the fuse block....

Otherwise, when it won't start, you will have to disconnect the harness at the gas tank and check to see if you have power for the fuel pump....when you turn the key to on, should only have power for 2 seconds....you will have constant power while cranking....

Was the vehicle scanned for theft deterrent codes?

Bad battery was probably why it wouldn't crank before......

So now, it cranks but doesn't start sometimes? Was fuel pressure ever checked when it wouldn't start?

When it won't start, keep a can of carb cleaner handy.....spray into the intake and see if the car starts.....if it does and then dies unless you keep spraying, then it is a fuel delivery problem...either the injectors are not firing or the fuel pressure is low.....could have a bad fuel pump relay, try swapping the relay with another in the fuse block....

Otherwise, when it won't start, you will have to disconnect the harness at the gas tank and check to see if you have power for the fuel pump....when you turn the key to on, should only have power for 2 seconds....you will have constant power while cranking....

Ok, after driving it yesterday and today the problem seems to have resolved itself. It starts up immediately when the key is turned. Maybe the new computer has 'learned' what to do. We'll see

Gonna add my .02 worth My daughters car had very similar behaviour off and on for about 2 months It would just act dead, she would wait 30 minutes then the car would start right up Other times it would turn over quickly with no hope to start. Answer: Fuel Pump in tank. Somewhere else in this forum folks told me how to check the fuel pressure, I got a guage at local parts shop on rental.

Gonna add my .02 worth My daughters car had very similar behaviour off and on for about 2 months It would just act dead, she would wait 30 minutes then the car would start right up Other times it would turn over quickly with no hope to start. Answer: Fuel Pump in tank. Somewhere else in this forum folks told me how to check the fuel pressure, I got a guage at local parts shop on rental.
Thanks all for the replies. Much appreciated. Replaced the computer. Problem solved. :)