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What is your fuel pressure with the engine running?

And you have ZERO fuel pressure with the engine off, but the key in the "run" position (fuel-system primed)? Sounds to me like you have a bad check-valve which is preventing the fuel rail from holding pressure.

That would definitely attribute to a "hard to start" condition. I would start with getting the fuel rail to hold pressure properly, and diagnosing from there.

 

Unfortunately I didn't get to accurately test the Fuel pressure with the engine running this morning. My fuel pressure gauge developed a leak, but the pressure was reading around 21 psi with the leaking gauge. That was before I pulled the rail out from the manifold. Now I have the rail out of the manifold with the injectors and fuel lines still attached, and it will not pressurize. Not sure why this is, could be the regulator but I wasn't sure if it could be due to the wiring harness being disconnected from the injectors and throttle body.


Would the fuel pressure regulator cause easy starts once second and impossible ones the next second? Could the check valve do this also?
I had no issues like this before the injector swap, so I thought the injectors were to blame but idk now.

 

UPDATE: Bought new fuel pressure gauge and it was showing that everything was peachy, got 40 psi on the rail no problem, it does go down some after shutting the engine off but I think that's just normal because the regulator and pump all are working normally and I tested them both.


Which led me to spark-sure enough, the only ignition component I hadn't replaced yet went bad. I was getting weak spark and pulled the coil-it was cracked badly. Just an update for those who do the swap in the future. A problem that appears right after the swap doesn't always mean it's the injectors fault.


Anyone have recommendations on a coil? All the ones at my local part stores have multiple reviews saying they are junk, but nothing else is in stock. I just need a durable and reliable one I can pick up quickly nearby.
For those wanting to do the upgrade, do it. My Jeep is a monster now, and that's with a crappy coil that barely works.


And a special thanks to Precision Auto Injectors, your product is excellent, my Jeep will chirp 31s now (which is awesome, btw)