I just swapped a new motor into my 2000 cherokee, it ran good for 2 days and several hours driving around the farm on dirt roads. I took it out and drove it about 10 miles to get gas, ran flawless until I cut it off and when I restarted it in ran real rough and the check engine light came on then started flashing as I drove it home. let it sit for about 3 hours and it started up fine but started running rough again after about 1 minute. any ideas? I will get a code reader this weekend but thought maybe someone has seen this before. Thanks for any help!

 

I'm not trying to insinuate anything but did take out the distrbuter? If so you have to realign the new one. Also when you reinstalled the CPS, did you make sure the bolts were tight?

It's usally the simple things that I miss, I'm dropping in a new engine in my 2000 cherokee this weekend and I dont know how many times I have rechecked all the different fittings.

 

What is the check engine light code?

 

The engine I swapped already had everything on it and I never removed the cps or the pickup where the dist would be. I don't understand why the jeep ran for several hours and never missed a beat, but now it just started running rough and the check engine light is on? I rode around for hours after installing the engine and it never missed a beat? I will get a code reader this weekend and see what it says.

 

Is there any chance that the CPS was damaged or hit during the install? Keep us up to date on what you find out with the code checker.

 

hopefully the code checker will tell you whats wrong...

 

he has a 2000 they dont have dissy's

 

Let's just hope that the code checker don't see any major problems on your engine...

 

Going back to your original post, u said it ran fine, and then u went to go get gas. Did the running problem happen right AFTER you got gas? If yes to this question you got bad gas, a bad fuel pump, and or a clogged filter.

The flashing check engine light means survere mutlible miss fires. Check fuel pressure, if it is low, replace fuel filter, if the fuel pressure is fine, drain gas and replace.

 

Has anyone seen a problem like this before? Sure, several times but in each case I used a code reader to diagnose.

Even if there was no CEL, a code reader can show you pending fault codes as well as allow you to read data to help diagnose, depending on the reader.

Kind of almost impossible to gather a guess with a problem like this without reading fault codes.

Absent the code reader, the only thing you can do is go over the motor again and visually/physically check that ALL connections are in place and tight.

You could go about and disconnect and reconnect all electrical connections to make sure one has not come loose, but here again the code reader will point you in the direction of the offending circuit.

OBD Code Reader <--- one of the best investments you can make, and today they are soooo inexpensive. They pay for themselves almost the first time you use one.

 

He never said he had a "2000" engine. He said he had a 2000 cherokee. I have a 2000 cherokee and I just got an engine that seems to be a "93" or around that time frame. It had a distributer that I had to get rid of and put my stuff on, that's why I asked about that.

x2 on the code checker, That will be my next purchase ( I should have already got one). When my engine blew it didnt trip any codes.....weird.

 

I got the code reader, heading out to see what it is!!! It actually started running bad when I left my house to go get gas, so I think the problem is something other than gas. B back with codes soon.

 

OK, code is P0204 injector circuit open cyl 4. So what does this mean, and how do I fix it?

 

Heat soak? I know the 2000+ 4.0's had that issue. Maybe someone else can better explain it.

 

Sounds like your #4 injector is stuck open or stuck closed. Either way, you get too much gas, or not enough. That would certainly cause it to run rough. I would pull injector #4, clean it really well and then give it a test. Maybe look up how to hook it up to a 9-volt battery and test that it opens and closes.