Hey guys, I have an 87 Cherokee with the 4.0 in it. When you first start it in the morning it has to crank for about a full 2 or 3 seconds, but then kicks right over. Doesn't sound like a long time, but if you look at your watch and count 3 seconds and picture cranking, it's pretty long, especially when you figure most cars will crank right over in 1/4 or 1/2 a second.

Once it kicks over it will run nice and smooth, but then drop idle and runs rough like it's missing, then recover itself and run smooth again, like someone gave it some gas. It will do this constantly while idleing cold, and eventually gets better when it warms up, but will still slightly do it.

When it's warm it will only crank for about 1 second before kicking over, so I was thinking it was fuel related, maybe a bad injector, but I've been told that an ignition coil on it's way out would give me a hard start, just don't think it would cause the rough running and recovery though. Plus when your driving the thing runs great and has plenty of power and is pretty quick for an old Jeep with 165K on it. It's been doing this the whole time I've had it, about 5K miles and hasn't gotten any worse or given me any trouble, just been too lazy to get around to figuring it out.

Was it normal for these older 4.0's to crank a bit longer? Seems to me I have heard these engines around cranking longer than most, but I could just be making myself nuts.

Sorry for the long post, just figured I'd give all the details.

Thanks, Mike.

There is a condition where the fuel "leaks back" into the tank while the engine is off.. To test this go out in the morning and turn the key to the "run" position without hitting the starter. Leave it there for a 10 count and then hit the starter.. If this works just do it every morning as it is easier than the repair...
Fuel is usually the culpret in extended start problems..
One injector wouldn't usually cause the problem indicated.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

Thanks Jim. I have actually tried that before with no results, have even tried turning the key on to prime the fuel pump(10 secs or so), then off again and then on again to prime again. Still starts the same every time, and has that rough/smooth idling problem afetrwards.

It consistently does the thing where it will run real rough after starting like a bad miss and then smooth itself right out, then back to rough and so on, it will do that all day if I let it idle....it almost sounds like when an A/C compressor kicks on and off, but the A/C isn't on (doesn't even work, so). Or like pulling a plug wire off and putting it back on.

Sometimes when it's real hot out, like in summer when it's 100 out and it's in the sun, if it's the first start of the day it will start real quick, but usually it has to crank a while like I mentioned. Sometimes actually it sounds like it will start to kick over for a second and crank faster, like 1 or 2 cylinders fired, then crank normal again and then finally fire up like usual.

Doesn't get any worse, just stays the same and drives great too. Idle smooths out when it gets some heat in her, but still always hunts up an down.

Thanks again.

Did the crank then it sounds like a cylinder or two start to kick then cranks faster for a split second then back to normal crank before starting thing this morning again, then idled real rough until it got some heat.

Any thoughts? Could my ignition coil be on it's way out, it may original in this 87.

Hey Jim, you mentioned a fix for the hard start problem, and that just turning the key on for a 10 count is easier than the fix, if it worked.

Just wondering what that fix was, and how to check to see if that's the problem.

Thanks.