2000 XJ Starts Really hard

:thumbup: 4.0/auto/242/ 96k miles. I just put a new fuel pump and tune-up on the wifes XJ because you had to crank it for 10-15 seconds before it would start and then it would stumble for a few seconds before finally running smooth. This happens everytime you start it no matter what and has happened for a while now. I dont know what to try next? Fuel injectors? I dont think it is the CPS. Thanks for any help

:callme:

You must have bought an inexpensive fuel pump from Advance or Checker/Kragen/Schucks. The check valves on those pumps have been known to fail within 12 months. Yours might have been a Monday morning built pump.

The best way to deal with long cranking times on the 1997-2001 is to crank the engine for about 3 seconds and then shut off the key and crank it again. My 2000 has had a bad check valve and long cranking times for several years now. It always starts on the second crank, sometimes runs rough for about 10 seconds and then is fine. I am too cheap to buy a new fuel pump until it stops working completely.

You may have a fuel injector that is leaking down and dropping the pressure in the fuel rail.

A good place to start is to hook up a fuel pressure guage so you know what's happening with it. Otherwise you will be just guessing and thowing money at it.

Your symptoms do match up with a leaky fuel injector. When an injector leaks, it provides extra raw fuel to that cylinder and that takes a few seconds of run time (stumbling) to clear it out. Time for some fuel pressure testing to try to isolate.

How do I go about pressure testing it? I could see hooking up a tester to the fuel rail, but how do you pin point one injector? Thanks for the input, I got the fuel pump about 4 months ago at oreillys where I get all my parts without issues thus far. When I put the pump in it started better but now seems to be gettting worse again.

any advice for figuring out which injector is bad?

Anyone? I am still having trouble