It wont start using the key unless I manually prime the fuel pump. I have swapped out the crank and cam position sensors with known good mopar pieces. Fuel pressure when using a jumper wire provides 41 psi engine off. Start the engine with relay in place gets 35 psi idle with regulator, disconnected from manifold goes to 44psi. Manual prime and clapping the feed line will bleed down to 0 psi in 1 hour. With the fuel rail removed from the intake manifold all 6 injectors can be seen firing and at rest do not seep. I have no visible fuel leaks under the vehicle or in the engine bay. I have a new regulator coming and will swap it to see if there is any difference in fuel pressures. If I turn the ignition to start but only for a moment (blip the starter) and leave the key in the running position after about 20sec I can feel the fuel pump, asd and abs relay click on and off a few times. The rail will prime when this occurs.

This leads me to believe that the ignition switch is faulty (not providing constant power to the ECM during cranking) or that the ECM may have an internal flaw. I have noticed with my scan gauge viewing live data I will lose data connection frequently while the engine is running.

Some additional items that have been swapped out are the coil, cap and rotor. The coil has visible bulging with cracks in the housing and ohms at 11.5k. Cap terminals and rotor were covered in slag, once clean severe pitting and general poor condition were noted.

Once the engine has been started using a manual jumper wire it runs as it should.

Thoughts are welcome, I think i may be looking for a new ECM.

 

Check your grounds. A lot cheaper than an ECM and a lot more likely. Also check your + battery connections, both of them.

See Cruiser's Renix tips. Lots of good info.

 

I removed all grounds and cleaned them with no improvement. Replacement PCM shows good results. A few more test starts should confirm the fix. Key to on position primes the pump now. Be careful what you wish for I was looking for a defective SBEC2 PCM. I guess I have one now.

 

Yes - this sounds like a common PCM issue with 91-95 XJs. It starts as a weak starting issue and then deteriorates to a long crank, generally worse when it gets cold. I was swapping my PCM for a new one anyway (the original was the wrong part number) and since doing so last winter I haven't had any issues at all.

And you should have asked about a faulty SBEC2 PCM - I still have my old one kicking around.

 

I think I still have the post open in the wanted section. If i screw up on the first one I'll let you know. Good to have a mulligan.