She has Strong spark and fuel coming out of the valve on the rail. She is cranking and cranking and back fires out of the intake every so often.
Every once and a while she will hit a luck and stumble and the process repeats. What should I check next?
Also she is a 2000 she is my dd and need her back

 

You say you are getting spark. Is it a strong BLUE spark Our XJ's need a good blue spark for them to catch. Also you need to check the fuel pressure. Not by just pushing the valve. You need to check it with a mechanical pressure gauge. If I am not mistaken you need 49psi, + or - 5psi.

 

A free simple check that happened to me on this engine when it was in the jeep. It would die randomly and then It wouldn't start it would just backfire. I investigated and found the wires pinched. I pulled them apart and taped up and worked until the engine gave out. I was getting fire but the Jeep did not like these wires touching. The Distrib cap pinched them and It was creating a short.

This is just an out of the box possibility.

 

2000 does not have a distributor cap.

 

Yeah it's bright tomorrow I'm gonna get a fuel pressure gauge and check. If its low does that mean I need a new pump?

 

Very possible. The filter/screen may be plugged. Unfortunately that is part of your fuel pump located in the tank. You would be best off if you have to change it, Change out the whole pump assembly.

 

Then that isn't the OP's problem haha. I don't look at years enough lol.

 

He can always glue one on.

 

Couldn't hurt lol

 

So I got a fuel pressure tester on her and it's sitting right at 50 and seemed to hold it pretty good

 

Crank sensor next?

 

Normally there is no fire when they go out. But who knows.
easy way to test CPS

CPS: You can check it's basic function but be aware that sometimes the darn things can be 'intermittant' but still read 'ok' when measured due to engine heat/temperature. Even so, these tests will show up a borderline CPS more often than not.

Check the connector first
If you've just stalled out with same symptoms... unplug the CPS & plug it back in. If your motor fires back up you might get off easy, but don't count on it lasting forever. I dunno what doing this accomplishes other than cleaning the connector contacts enough to let additional voltage through to the computer. If unplugging & replugging worked then unplug the connector again and clean those contacts off. Then apply some OX-GARD, or other electrical contact cleaner & protectant (dielectric grease).

There is a distinct possibility that you're not getting a signal due to a faulty connector itself as well. Some people have cured their CPS problems by simply cutting the connector out of the harness and SOLDERING the wires together (Use heat shrink or electrical tape around the wire, of course!) Other's have replaced the connector with a newer, waterproof version from an electrical or automotive supply store.

Test#1 - Get a volt/ohm meter and set it to read 0 - 500 ohms. Unplug the cps and measure across the CPS connector's A & B leads. Your meter should show a CPS resistance of between 125 - 275 ohms. If it's out of that range by much; replace it. (* - Note: HO engines are measured from the B & C connectors and should have near zero ohms.)

Test#2 - You'll need a friend to help ya with this one.
Set your volt/ohm meter to read 0 - 5 AC volts or the closest AC Volts scale your meter has to this range. Measure across the CPS leads for voltage generated as your friend cranks the engine. (The engine can't fire up without the CPS connected but watch for moving parts just the same!) The meter should show .5 - .8 VAC when cranking. (That's between 1/2 and 1 volt AC.) If it's below .5vac, replace it.

Desperate last ditch tip to get home or a few more miles from a failing CPS: - Other than the unplug/replug trick... MJR passed on a trick of using a flat bar and a hammer to 'adjust' the CPS by smacking the CPS bracket and forcing a weak CPS just a tad closer to the flywheel. This lets a weak CPS get a stronger pulse and hopefully generate enough voltage to feed a good signal to the computer again. WARNING! - If ya smack it too hard... it'll go in too far and the flywheel will eat the CPS! Start walking.

Either way, if it fails ANY of the tests... you should replace it and save your self some major pain later. If not, at least carry a spare CPS but be aware that it's a royal pain in the *** to change on a cold motor and ya really don't wanna do it at night, on the trail and with a hot motor if ya can help it!

This one is a 'last resort' fix if you've replaced the CPS already & it didn't fix the problem. The issue is a crappy harness which this bulliten addresses through a replacement of the actual CPS harness. (They call it a CKP harness for some idiotic Daimler-Chrysler reason...)

 

Will bad cps make it back fire through intake while trying to start? It all started once I filled up the tank if that means anything

 

When My CPS went out I had no fire. It possible that it could hit enough to make it back fire but IdK. Spray a little starter fluid in the throttle body. If it starts I would think its fuel. If it don't start it would probably be fire which leads to CPS.

 

I got fuel and spark