Aman1022

Hi guys I've got a 89 xj that I've been fighting with for almost 3 months I've replaced the cps about 15 times trying to find a "good" one and every other ignition component that I know of including CPS ignition switch ignition control module coil distributor. I keep coming up with what seems to be very random stall and die. And after these last few weeks it has finally gotten to the point of no start at all and no crankshaft position sensor has fixed this I'm about 300 or more between all these parts and I need help also have checked and added grounds and have not found any broken wires possible computer? I have no idea

gat

What if any codes are present? What is the fuel pressure at the rail before turning the key, after turning the key to on and holding it there for three seconds, while cranking, and 20 seconds after cranking?
Is there spark present at any or all spark plugs?
Will the vehicle start with you pouring a teaspoon of gasoline straight into each cylinder thru the spark plugs holes before trying to start the engine.

Oswalla

Now that it is dead should be easier to troubleshoot. Fuel, Spark and Air, Let us know if you got those. You won't have codes, Renix unable to store or throw codes, live data only if you have the right scanner.

CPS can be tested with multi meter. Bad one will cut spark and injector pulse. A noid light will help you see if injectors are firing, spark is easy grab a wire and crank .

Aman1022

No spark at all I've tested CPS after CPS and near as I can tell they are fine I dont believe I have fuel going into the cylinders while cranking but have a solid 30 psi at the rail when cranking air is a defint have plenty of air and this no spark is directly at the coil the ignition control module is getting 5ish volts at the two prong single wire connector also no joke have been threw about 20 or so CPS including a high altitude CPS

arto_wa

That works fine, another method would be just spraying carburetor cleaner from a spray bottle into intake while cranking the engine.
That stuff will fire up about the same in the engine as gasoline will.

Learned that trick from a marine engine shop where they start up a bunch new gasoline engines every day.

Aman1022

Can a CPS be ruined by atf the tranny leaks last few sensors I've pulled out have been oil/atf soaked not sure if that might interrupt the connection

Oswalla

Not that quickly I imagine.

Check your injector pulse too if your thinking cps circuit is not working. Noid light is easiest but you could have a buddy crank while listening for the clicking at an injector or 2. Use a piece of vacuum hose to your ear and injector if you have crappy hearing like me. Should smell fuel also if its pulsing and not igniting by spark.

Oswalla

I just realized your new here so maybe you have not seen Cruiser's Tips yet. See post #4 also.

https://www.cherokeeforum.com/f51/cr...x-tips-153657/

http://cruiser54.com/

cruiser54

Yup. First thing. Check the grounds at the dipstick tube stud.

If it were me, I would complete tips 1,3,4, and 5 before doing anything else.

Aman1022

In this mess I've checked every ground by the dipstick to my knowledge there are 3 or 4 including my battery negative the coil and ignition control module are new so no reason to clean them I did pinch the contacts a little tighter I've tried the wiggle test when it was running and no wire made a difference

Aman1022

I've never smelled fuel out the tail pipe and the plugs always come out looking great I'm really lost at this point

Aman1022

So today I went out to the jeep repluged in my computer after unplugging it last night and this morning it started looked at the plugs they are a bit dark like over fuel spark is heavy blue

Aman1022

This is what all the plugs look like my experience this is to rich gap is a round 40 could this be the problem

SatiricalHen

Go through all of cruisers tips to start off, and after you have done all of them check air, fuel, spark, and compression. A very useful thing when diagnosing these renix jeeps is the use of a scanner (don't remember which one works I just know they call it the brick) or an Renix Engine Monitor (REM).

Aman1022

Ended up being the computer thanks for you're guys advice it's very helpful to be able to bounce things off others lucky a new reman for me was only 80 bucks so the jeep is back to her former glory