Bought this jeep recently. Put new battery, alternator, and starter on it. Also replaced the valve cover gasket. It will not start. We are at a loss for what else it could be. Anyone able to help me out?

 

Turn the ignition on and off three times in succession and tell us what code appears on the odometer, or plug in an OBD 2 in the receptacle under the left hand side of the dash to give you a fault code, then we can go from there. At this point, we don’t have enough information to analyze your problem, once you have a fault code, we will be able to steer you toward a solution.

 

One more thing, give us year, and model I.e. XJ, ZJ, WJ etc. the more information, the better to help you. Details are helpful, such as: turns over but doesn’t start, doesn’t turn over at all, etc. Throws fault code POXXX etc. Glad to help, just need more details.

 

You might have a Laredo version.

 

From the header, I can tell it's a 2001 WJ, but what engine? It's probably a 4.0 since you replaced the "valve cover gasket", singular. It's not good to guess.

The "key trick" for getting trouble codes is to turn the key on, off, on, off, on and wait. Any trouble codes will appear in the odometer in sequence, then "done" will appear.

 

Can we assume it ran when you bought it? Not sure about a Grand Cherokee but on the Cherokee 4.0 engine the crank position sensor (CPS) wiring is close to the firewall side (toward the rear) of the valve cover. Check if any wiring might have been damaged when removing the valve cover or got caught under the valve cover when reinstalled. If the CPS fails or the wire is open or shorted to ground the engine will crank but not start.

 

In my experience, a failing CkPS won't set a code until it fails! Also, sometimes the same code will be set when either the CkPS or the CPS has a problem. Most people don't realize the Cam Sensor has nothing to do with ignition timing. It controls injector timing.

Did we lose the OP?

 

We changed the crankshaft position sensor. It cranks but doesnt run. When it seems like it will a big woof sound comes from the air filter box. It did run when we bought it but since then it wont start. We did the key thing and the only 2 codes that came up were 1489 and 1490. We plugged a scanner into it and no codes.

 

Is there spark (strong 'snapping' blue sparks)? Is there adequate fuel pressure? You can borrow a fuel psi gauge from box stores.

Because of the coil pac it is different to check on the sparks for a WJ.

(copy and pasted):
You should make up 6 separate jumper wires about 2 feet long. Pull the rail and flip it upside down. Insert 6 sparkplugs into the rail. Attach one end of a jumper wire to the threaded part of the sparkplug with a large mouth alligator clip and attach the other end of the jumper wire to engine ground.

Once all 6 are hooked up this way, you can then perform your engine cranking test while observing spark on all 6 plugs. You are looking for a strong, BLUE, snapping spark. Yellow/orange/white indicates a weak spark.
(end copy and paste)

Adequate compression is necessary in order for the engine to be able and run too. You can borrow a tool from box stores to check compression.

It could be the Camshaft Position Sensor (CPS) since it sounds like you are saying it kind of wants to spit and cough out of the airbox like that, possibly? Other people have reported spits and coughs out the intake when they had a bad CPS. Have you looked up the procedures for testing both, the CPS and the Crankshaft Position Sensors (CkPS)? It would be good to verify they are okay.. and their wires.

What do all of the spark plugs look like? Are they fouled? Wet-fouled? Or, dry-fouled?