I have owned XJs for about 10 years so not a complete newbie. 3 days ago I bought this Grand Cherokee, auto, 145k miles, 4.0l, 4x4. The guy bought it a year ago and it was his daily driver until a couple of months ago when it started to run rough. He has changed out the computer, starter, distributor, cap, rotor, plugs, wires, fuel pump, ASD relay. And he said it would run for 15 or 20 minutes then quit and he would have to let it sit for a few hrs and then it would start again.

While buying it, it cranked a long time about 4 times and then started but was running very rough, I drove it up the street then and loaded it on my trailer. Got home and started trying to find out why it was running rough, started it probably 6 times. Next morning it would not start so I worked on it then had to leave, late after noon it fired right up.

Yesterday it would not start and I had no fuel pressure so the pump was not coming on. I jumpered the fuel pump relay socket and got 35 lbs of fuel pressure but it would still not start.

This morning still no fuel pressure so I put in a CPS crank position sensor, from my 94 XJ and still no fuel pump so I messed with doors, locks, etc a bunch of times and the pump finally came on but still no start so I put the original CPS back in and still no start.

That is all the info that I have from the PO so any ideas? I have spent hrs online researching and I am at a loss. No codes show up.

 

CEL?

 

No CEL.

 

I just went out and swapped some relays again and did the door lock/unlock and the dang thing started. Idles fine but when I give it gas it runs very rough so tomorrow I will clean the TB and if that doesn't do it I will do a compression test.

 

Went out this morning and it started right up! Ran like crap but started.


What is the rocker switch just to the left of the radio?

Where can I download a free owners manual?

I read about a spacer for a crank position sensor, mine doesn't have one unless I missed it, is it suppose to have one?

 

Some CPS come with a cardboard sticker on the end face to set the proper space from the flywheel. Some don't. This sticker gets wiped off on startup.

 

After doing a lot of research I see that some CPS are one bolt and they have the spacer but that the ones with 2 bolts like mine do not. Hope this helps others that are confused like I was.

 

Got the security system disarmed so that part is done.

It starts up fine and idles fine but when I give it gas it runs really rough. I cleaned the TB and no change and have not done the compression check yet.

Any ideas on running rough and what is the rocker switch to the left of the radio for?

 

Pulled all the plugs that are suppose to be new and everyone has black carbon on the white porcelain.

Found the notch for timing and put it on zero while #1 was tdc. Took off cap and rotor was pointing to 12:00 instead of toward #1 on cap at 5:00. Pulled distributor and it does not have the plate and holes to put in a punch to line it up like I saw on a youtube vidio so I moved oil pump to 11:00 and when I put the distributor back it the rotor pointed toward #1 on cap and the slot for bolt lined up with hole.

Now it won't start or even fire. Any help here?

 

When you set the engine to TDC, are you sure it was on COMPRESSION? It could have been 360* out, as in on exhaust. After all, it was running before.

 

Real sure I was on compression and piston was at the top. I wish I would have marked where the rotor was before I pulled the dizzy but since it was running crappy I thought it being off was the problem.

Last night I adjusted the oil pump so the rotor was pointing at #1 post on cap and still no start. I did read on a renix that it should be just past the post but not sure if that is true for this motor.

 

I just read the service manual about changing out the distributor and it says nothing about TDC and compression stroke, just says to put timing mark on 0.

When I pulled the dist. I was at TDC on the compression stroke and the rotor was not even close to pointing to #1 on the cap but as I said I did not mark it and don't remember for sure where it was.

Am I missing something or what?

 

Runs perfect now, distributor was put in wrong. Next is the speedo doesn't work and motor doesn't get warm enough for heater to work.