very rich xj

ok this is my first jeep its a 1990 xj with what im told is a reman moter from a new modle. not sure. it is very hard to start and runs very very rich. looks to hav a new coil, plugs, wires, cap n rotor, tps. it was way over full on dip stick with very gassy smelling oil and glossy black spark plugs so i changed oil and new plugs. no change i read that they are bad for injectors going bad so i pulled a known good set from f150 with #19 no change tryed a set of #24 mustang injectors no change its got about 40 psi of fuel pressure i can unplug injectors and no change but 4&5 will cause it to cut off if unhooked almost seems like it could be running off of those two cylenders???? all injectors are getting a pulse according to noid light any ideas or suggestions? agin first jeep!!

Note from DJ
This information may help you identify what the previous owner swapped into your Jeep
Block casting no location can be found hear in post # 2 by CJ7-Tim
http://www.jeepforum.com/forum/f11/4-0l-serial-number-location-995174/

Head casting number by years
It is easy to determine what head you have. On the driver’s side, about halfway down the cylinder head between #3 & #4 fuel injector but below the valve cover clean the lip of the head with a rag or solvent if really greasy. With a good light, you can read the casting number of the head.

Head casting number by years
Casting numbers are as follows:
Year............Casting No
1987-90......2686
1991-95......7120
1996-99......0630
2000-01......0331

The major player in fuel mixture is the MAP sensor located on the firewall and has a tube/hose going to the throttle body.

MAP sensor tube
There is a brittle little tube. It comes out of a rubber plug, low on the engine side of the throttle body. It runs back to the firewall, then up to your MAP sensor, behind the valve cover, higher up on the firewall. It has one vacuum line as already mentioned, with a 3-wire plug in the bottom.
CRUCIAL!! The MAP sensor will tell the ECU to dump fuel with little to no vacuum to the MAP. Any crack or blockage and it will be pig-rich. ( black smoke, fouled black plugs, must hold your foot to the floor to keep the engine running). You can pull the line off the MAP sensor and feel for vacuum with your finger. If it runs!
A visual inspection usually reveals any issues with the line from the throttle body to the MAP sensor.

Also, since the engine was replaced, are you sure all the critical ground connectors are at a clean and shiny engine dipstick tube stud? Not attached over a bunch of paint? Read this below about the grounds.

Renix Ground Refreshing
The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, failed emission tests, and wasted money replacing components unnecessarily.
The components grounding at the dipstick tube stud are:
Distributor Sync Sensor, TCU main ground, TCU "Shift Point Logic", Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.
The factory was aware of the issues with this ground point and addressed it by suggesting the following:
Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.
Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.
While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.
Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.
First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4" socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.
A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18" long with a 3/8" lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.
A further improvement to the grounding system can be made using a #4 cable, about 10" long with 3/8" terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.
For those of us with Comanches, it’s very important to remove the driver’s side taillamp assembly to access the ground for the fuel pump. Remove the screw holding the black ground wire. Scrape the paint from the body and corrosion from the wire terminal. Reattach securely.
If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.
　
Revised 03-04-2013

An added note, check your distributor indexing. Complete procedure can be found in the following link, post 13.

http://www.cherokeetech.com/VBull/s...uiser-s-Mostly-Renix-Tips&p=103796#post103796