Why wont my olds Cutlass cierra start when its.

How long since a tune-up? Use a gage and check fuel pressure. Check for applicable mil codes. I believe your vehicle is computer controlled. If so, you should be able to check mil codes, yourself. You use a jumper wire between the A & B terminals at the datalink connector. Turn key just till the dash lites come on, no further. The mil on the dash starts flashing, you count the flashes to get the codes. Your looking for two digit codes.

Also, when the problem is ongoing, have a helper crank it while you visually check for spark at the spark plugs, just to be sure.

You can try a little starter fluid in the intake, when problem is ongoing, see if it will bust off. There is a safety issue using starter fluid, any flammable spray is dangerous. Open throttle valve spray just a little, stand back from vehicle, have helper crank. Safety is your responsibility. If it does start, its a fuel issue. Let us know about any possible codes.