DFlintstone

You reach up past the front drive-line, and hold it from the front with your left hand>

11mm socket > 3 inch extension > universal > long (18-24 inches of extension). Your feet are sticking out under the passenger side, you can reach up past the front drive-line with your left hand to hold the CPS from the front. Your right hand is on the ratchet way back by the tranny cross member. If you tie a long string on the old plug, you can use it to haul up the new. Toss that piece of plastic if it's still there, and do not drop the bolts in there! Echlin # CSS980, (from Napa, for 87-90), should be fine, but some prefer to go to Jeep. I wouldn't bother with anything else for that.

If your left forearm is bigger than a quart Mason jar, you might consider removing the front drive-line. Also You might cut your old CPS wires if they go through a deal on a bell housing bolt, then be sure your new are held somewhere safe.

The second one is REALLY easy!

jretzky

I bought a actron vacuum and pressure tester kit.
It was $27., but I haven't opened it yet.
Undecided if I should use it or not.
Could of bought a actron fuel pump pressure gage (only) for $45.
The one I got reads engine vacuum & fuel pump pressure.

The gage reads 0-30 inches of vacuum and 0-10 PSI.
What PSI are the fuel injected 89 4.0L suppose to read?
Still trying figure out what's making this jeep run intermittently.
Where do I take a vacuum test at and what should it read?
Please!~HELP------John

DFlintstone

89 should be about 39 Lbs with the line off the regulator, around 10 less with it on.

Any intake vacuum port will do for vacuum, that one there to the regulator would be fine. About 18 inches at idle. My old thing is a bit less. If you google vacuum tests you will find allot. Also cruiser has a thing in his tips.

Sounds a little spendy for a regular vacuum gauge, (they all do some pressure as well). If it has a hand operated, (or otherwise) vacuum pump, those can be handy for finding/checking for leaks in the lines and stuff. (like heater diaphragms and the ball)

jretzky

I wonder why the fuel pressure (PSI) gage (I bought) only reads to 10 psi when our vehicles fuel pressure is around 30-40 psi?


John
PS. Not trying to be difficult.

holycaveman

Ever check your tank/fuel for water?

DFlintstone

No Problem. Carbureted engines typically run at 5-8 Lbs. I just noticed one of my "vacuum" gauges has that feature. You might return that and find a vacuum gauge for allot less.

GRohr

I was having similar problems on my 87 a while back and I have done a lot since to make it run perfectly. Go and just rent the fuel pressure tester from Autozone rather than buying one, that is what I did and it is super easy to use and free! My backfire issue and sputtering problems came around after I replaced the ignition coil. My engine never died but the backfire was ridiculous. I ended up having to replace the distributor and distributor cap which had a ton of oil in it. That solved my issues and was easy to do. Just a thought.

I highly recommend doing Cruiser's Renix tips as it helped my motor out a ton.

jretzky

Ok!~Last night I hooked up an 60 psi gage to the fuel rail and started it and it ran 30 psi and when I removed the vacuum line on the it was 40psi (exactly what it is suppose to be. When I turned on the key I heard the fuel pump run. Then I ran the engine and pulled a part the connection to the CPS and the engine died right away...must be good.
I am going down the list of Cruiser and tonight I am going to check the IAC and throttle body. There are two wire plugs in to the throttle body.
Which one do I want to pull? Looks like two screws on each.
Do I have to take the throttle body off or can I clean it with it on the engine...maybe running? I'll clean the O2 sensor also.
Then after that I'm on to check the coil and the distributor.
What goes bad in the distributor? I have a new cap & rotor.


Going down Cruisers list.


Thanks!~John

GRohr

The square one and here is a good link:

http://www.pirate4x4.com/tech/billav...ion_manual.pdf

I would test it before you remove it and clean it. If you take it off you will need to adjust it which isn't hard but can sometimes take a while to finely tune it to get the perfect numbers (the TPS is the only thing that I dislike about the Renix system compared to 1991 and up which don't need to be adjusted). The TPS could deal with the no acceleration problem but I don't see why it would make your cherokee backfire at all. I would look into the distributor as that would deal with the backfiring but that is just my 2 cents. Something else that I did which helped a ton with my cherokee's loss of power was cleaning the fuel injectors REALLY well.

I replaced my distributor as there was oil getting into it and was pretty cheap on RockAuto. I am not sure if just the cap needed replacing or if the distributor itself helped fix everything.

jretzky

Thank you for the information (Manual) I appreciate that. IT'S GREAT INFO.
I am not having the back firing problem any more I believe that was due to the CPS wires getting burnt on the exhaust (also plugs, wires, cap & rotor). Last night I cleaned the throttle body and the IAC.
They both were very dirty. I didn't see your post till today and removed the IAC and cleaned it and put it right back in and the engine runs fine.
Now the existing problem is...after it sits all night it acts up in the morning only.
It has little or no response to the gas peddle, but the engine runs.
I am slowly making progress. I read up on the O2 sensor last night and now knowing the (specs) 5-7 ohms for a good one that is my next test tonight.
I feel like I am narrowing things down (trying not to get frustrated).
My son came over last night with his book on electronics and sensors and I learned a few new things (being a mechanic from the 60-70s).
He still believes the O2 sensor is bad since my spark plugs are black and you can smell my Cherokee a long ways away....we see.
Until tomorrow...I will continue on!~John
Funny a friend of mine asked me what happened to the good old days with a screw and spring for the idle. Don't give up on me!!!

syncview

spark plugs being black can also mean that you're running rich due to a vacuum leak.

the vacuum leak makes the mixture lean, O2 sensor reports the same to the ECU and the ECU increases the duty cycle of the injectors to make the mixture rich enough.
since the leak is causing unmetered air to enter the engine, it not running properly

I'd check and confirm that you have no vacuum leaks

since you have ruled out fuel pressure/dizzy cap/rotor/plugs.

have you checked the spark plug wires?
if they are arcing or are bad that would also produce same kind of symtoms. Specially if you feel like a power cut when you depress the accelerator, it is mostly likely a spark plug cable or two leaking spark.

you must've confirmed this already but just giving you an idea - check if the spark plug cables are fitted in correctly as per the firing order.


EDIT:

this kind of a problem can also be caused by a bad TPS/MAP signal wire.. IIRC they had a signal wire from the TPS and the MAP joined which goes to the ECU.. if the wire is cut from either end or shorted to ground - it will cause problems.

GRohr

My first cherokee had an injector fail and was dumping gas into the engine. I had zero acceleration and it made my catalytic converter glow red hot and just baked the inside of the cab as the cat burned the remaining gas. It took me forever to troubleshoot my way down as I started with the TPS, MAP and leaks. I ended up replacing the injectors as I got frustrated and replaced every single fuel related part (fuel pump, sending unit, filter,TPS, MAP, coolant temp, air intake temp, fuel regulator and then finally the injectors). I went from getting 6 miles a gal to 18.

I am not sure how to test injectors but that is something that you could look at.

syncview

Oh yes a leaky injector or injectors can be problem as well. .

One way to identify an injector related problem would be to start the engine and disconnect the injectors one by one.. in this case if an injector that is leaking is disconnected, the engine should run slightly better..

Another way would be to separate the injector rail from the manifold, place a shop rag under the injectors. . Power up the fuel pump and check closely if any injector leaks. Any injector that leaks more that 2 drops a minute needs to be replaced. .

DFlintstone

At some point the TPS needs to be checked/adjusted. In your shoes I suppose I'd put that one to bed. (spray the screws ASAP)

If it has stock injectors, you might want to can those pieces of crap and get some 746"6 for it. Serouisly, you will love the way it idles and runs, and if you pick up even one mpg they will pay for themselves at some point.

jretzky

Man- this is crazy!!! I don't understand what is going on with my Jeep to a certain extent.
The problem now is that in the morning only, the engine runs rough & has a surging effect when you step on the gas. I am really surprised that we are at 4 pages of posts now and I haven't fixed my problem.
I blame it all on sensors. Life was much easier before they came out, but not according to this new generation. Some cars have 15 to 25 sensors that tell the computer how to make the vehicles engine run. Some vehicles have up to four oxygen sensors. I don't know what to believe after going to Jeep forum & Cherokee forum plus other sites to figure out what is going on with my engine.


So if it take compression, spark, and gas to make an engine run. I am trying to narrow it down. I would rather have my Jeep break down and not run at all then to have it intermittent like this. According to the census among people (that have the same problem as me) is that most of us have spent lots of money replacing sensors and a lot of times that's not the problem.


I'd like to figure out how to make this Jeep run in the mornings-good one huh?
Here are a few questions...
How do you test a O2 sensor. One guys say check it with an ohm meter (5-7 ohms).
Another guy says he walked into a parts store and checked a brand new O2 sensor and the meter was all over the place. Another guy said it's something else not the O2 it affected by the IAC,TBS, cam sensor, CPS, Cap, rotor, plugs, fuses, and all the wiring. I'm sure I'm forgetting a lot more.
Just laughing!~ John