trouble starting

i know that this is probably somewhere else on the forum but i have not figured out how to search the forum yet so i'll ask again.

I have a 89 cherokee 4.0L 4x4. when i go the start my jeep it tries to turn over but does not start. usually on the third try it turns over. once it is on it has no trouble running besides getting 3-4 mpg worst but that might be unrelated. i live at 7000 ft but it is usually around 80 degrees outside so i dont think it is the temperature. it does this at sea level also but usually it will start on the first try with some difficulty. so the elevation might be affecting the problem.

the starter, battery, alternator, spark plugs, wires, distributor cap and rotor are all under 2 years old. i have checked the fuel pressure at the fuel rail and is within the operating range but is on the low side. all the gages and lights work fine.

it seems that this is a common problem with jeeps but i have found a solid answer yet and was hoping that you guys could help.

if the suggested fix is expensive please suggest how to test it, so i can be sure
thanks

After it's been sitting awhile, without touching the key, check the Shraeder valve on the fuel rail, and see if you get a good spray, or just a dribble. You say it has pressure running, so I assume you have access to a pressure gauge. Or, maybe hook up the gauge, start it, turn it off, and see how long it will hold some pressure. It should hold a certain percentage at least overnight, or longer.

How about you try describing the problem again.

Does it crank, no start? Does it crank poorly/weakly, no start? Does it crank over like a raped-ape, but no start?

Just not sure from your original post.

when i go to start it the engine is turning and trying to start but it won't fire up. it usually takes about 2-3 tries of about 10-15 seconds. i have not found any correlation between the engine temperature or the outside temperature

Ok. Little history lesson. The Renix era 87-90 XJ with the 4.0 engine has to "spin up" to 300+ rpms before the crank sensor will generate a strong enough signal that the ECU will fire the spark.

So, couple things to do:

Make sure your tune-up items are good--plugs, cap with brass contacts, rotor, plug wires.

Make sure all of your grounds are renewed--stripped to bare metal, treated with an anti-corrosion agent, made real TIGHT. First important ground is the POS braided strap from the rear of the head, driver's side, to the firewall as that is the ONLY unibody ground and replacing it with a 4 or 2 gauge cable is a good move. Renew the dipstick grounds (ICM/ECU/o2 sensor and others)--these are critical. Remove the coil from the ICM and clean the clips that join them together, then treat with dielectric grease.

Upgrade your electrical system with heavier gauge cables. Good article on it here: http://www.olypen.com/craigh/charge.htm; check 5-90's website he has the best cables I have ever used.

Condition of the starter-solenoid and battery. If these are tired you will have prolonged cranking times.

Last, and probably least of your issues, do a pressure leak down test on the fuel system by attaching a pressure gauge to the Schrader valve on the fuel rail, run the engine, then shut it off and observe how long it takes the fuel pressure to start dropping. Could indicate a need for a check valve or new fuel pressure regulator.