I have a 1990 Cadillac sedan DeVille 4.5 engine turns over won't start try spraying starter fluid and still won't start check the spark plug wires the number one spark plug is broke replaced it still won't start so now what could be the problem

now you need to check compression...You'll need a compression guage. Check all the cylinders and compare the results...If you do have spark and (in this cas) a fuel sorce. the last thing you need for combustion is the right amout of compression.

Make sure you have fire to the plugs.

Chances are its an ignition problem if nothing happened by using starting fluid. Have you pulled the plug wires and checked for spark ?

You can try Alldatadiy.com for the diagrams.

Car not starting or turning over indicates towards multiple possibilities. It can be issue with battery or weak battery. But if battery checks out ok, then it can be starter issue or faulty alternator or problem with low fuel pressure or no spark at spark plugs due to dirty spark plugs or faulty ignition coil or injectors getting cracked or dirty and needs to be cleaned.

To confirm the problem, the basic troubleshooting is required.

Click this link below and follow the troubleshooting:------

http://technoanswers.blogspot.in/2012/02/car-starting-issues.html

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This will help.
Thanks.

Spray carb spray or starter fluid into intake hose then try to start. If starts then suspect fuel pump and or fuel pump relay. If does not start check spark. Pull off spark plug wire and ground to metal make sure no fuel is present and be careful not to spark yourself, crank car while grounding out wire if no spark suspect coil, fuse, ignition control module, crank sensor, wiring, or computer.

First, I would determine it is bad. I have a 1990 Cadillac Sedan Deville, and sometimes it doesn't turn over. But, if I toggle the switch a few times or up to 5 times, it starts to turn over and the car starts.

I have the same problem with a 1997 Cadillac Deville.

If you are set on changing it, here is a picture and instructions on how to test:
Starter TESTING Voltage Drop Test Fig. 1: Schematic of a voltage drop test
NOTE: The battery must be in good condition and fully charged prior to performing this test.

1. Disable the ignition system by unplugging the coil pack. Verify that the vehicle will not start.
2. Connect a voltmeter between the positive terminal of the battery and the starter B+ circuit.
3. Turn the ignition key to the START position and note the voltage on the meter.
4. If voltage reads 0.5 volts or more, there is high resistance in the starter cables or the cable ground, repair as necessary. If the voltage reading is ok proceed to the next step.
5. Connect a voltmeter between the positive terminal of the battery and the starter M circuit.
6. Turn the ignition key to the START position and note the voltage on the meter.
7. If voltage reads 0.5 volts or more, there is high resistance in the starter. Repair or replace the starter as necessary. NOTE: Many automotive parts stores have starter bench testers available for use by customers. A starter bench test is the most definitive way to determine the condition of your starter.
   

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Remember to disconnect the battery and remove the wires from the starter at the hex nut.

Then, remove the 3 or so bolts that hold the starter on using an extension and ratchet if necessary.

Hope this helps.

you need to figure out if your missing spark at the plgs,or check fuel pressure at fuel rail,you'll need at least 55psi of fuel pressure,but if you have had no luck spraying the throttle body,your probably missing spark

To avoid confusion, remove and tag the spark plug wires one at a time, for replacement.
If a distributor is not keyed for installation with only one orientation, it could have been removed previously and rewired. The resultant wiring would hold the correct firing order, but could change the relative placement of the plug towers in relation to the engine. For this reason it is imperative that you label all wires before disconnecting any of them. Also, before removal, compare the current wiring with the accompanying illustrations. If the current wiring does not match, make notes in your book to reflect how your engine is wired.



4.5L and 4.9L EnginesEngine Firing Order: 1-8-4-3-6-5-7-2 Distributor Rotation: Counterclockwise

Hope helped with this (remember rated this help) Good luck.

sounds like jumped timing belt maybe chain ,no spark is my guess if it turns over and dont even make a pop noise..