89 Jeep Cherokee 4.0 hard to start, bPLEASE HELP!!!!!b

Tim, the problem is that the leaking injector seal lets the pressure drop - you would see this immediately with a fuel pressure guage. Fix the injector seal! Open the hood and look where the fuel from that injector is going: straight down onto the exhaust. Are you sure the leak is from the o-ring on the rail? Both of the ones I've replaced were actually leaking around the electrical plug. For the first, the cure is new o-rings (careful, some kits have two sizes and compositions so put the right ones on the right end). FIX THE LEAK! It's a fiew waiting to happen.

Ty, yours sounds like a fuel pressure problem as well but since you don't see a leak it's more likely to be bleeding off pressure back to the tank. You have a pressure regulator on the forward end of the fuel rail that will do this if the regualtor is shot and leaking through. Try this: turn the key on and listen for the fuel pump to run (don't go all the way to the starter position). When it stops running, turn the key off then turn it back on to cycle the fuel pump again. Do this several times then try to start the engine. If it catches fairly quickly, then it's likely a pressure problem. To be sure, do the key cycle thing a couple of times then turn it off and press the center pin in the schroeder valve (oversized tire valve) near the front of the fuel rail. Hold a rag to catch any gas. You should get a decent spray even after waiting 5-10 minutes - mine holds a noticable pressure overnight. If it just dribbles out, then you know it's fuel pressure. Since you've changed the pump, it's most likely the regulator but there is a test for that so write back when you try the above steps. It could also be losing pressure through an injector leaking into the manifold so a couple more tests migh be needed. BTW, the 87-89 4.0 used a Renix fuel control computer and it takes relatively long to fire up cold under any circumstances (about one full turn of the engine). 30 seconds is way too long, but 5-6 seconds is not that unusual. The later MOPAR models catch right away.

For both of you, a fuel pressure guage is $12 - $18 bucks at the local Advanced Auto or Auto Zone. Worth the price is savings on unnecessary parts and agravation

-- Will Honea