1990 Grand Marquis 5.0 How do I remove an Injector?

Try several things...

Fuel injector cleaner
New fuel filters
Check for vacuum leaks
New spark plugs and wires

Then if the wire did not spark or knock you down it must not be getting spark. You could have a bad coilpak. If it sparks, then look at fuel side, like a bad fuel injector on #4.

There is a test system called Noid lights which plug into the wire harness on the injector. This will show if juice is going in, but a Voltmeter can also be used to verify power to the injector. The loaner programs at big autoparts chains may have Noid lights to lend.

Now if you know the power is reaching the fuel injector, you probably have a bad injector. Disconnect the wire harness to the injector and use an Ohmmeter to test the coil inside the injector. If it is bad it will not show Ohms.

How about the injector? In the engine junction fuse box the fuse for the injector power is in there make sure its not open

Give me some more information about this problem. May be i can help.

your car doesn't have a carbuterer, its fuel injected with a throttle body, and starter fluid id not a good idea, better to check for spark, fuel pressure and injector signal , one of them is missing

thoroughly clean area around injectors,and then blow with compressed air so no bits will fall in the holes when injectors removed.loosen main injector pipe nut,remove return fuel line,dont lose copper washers,put special fuel bolts back in top of injector firm[by hand] undo holding down bolts evenly,undo fully injector pipe nut,.gently pry injector loose,and remove,making sure sealing washer at bottom also comes out..while I dont specifically know this particular engine,this guide applies to most diesel motors.I have rebuilt a 6v72 detroit motor,yrs ago.Assembly is reversal.may need to crank over to bleed diesel at injector,always use new sealing washers.

The EGR valve may be sticking open.... most likely ...

Possibly clogged fuel injectors... (not as likely). Use a brand name fuel injector cleaner ($6 AutoZone) or "complete fuel system cleaner ($8 AutoZone). No store brand stuuf, just name brand.

Check the fuel injector pulse now the injector should flash on and off.. if it does not then there is an electric problem could be fuses or injector relays. Remembe injector is 12 volt solined.

Mass air flow sensor.

need a noid lite to check injector and coil pulse