Has spark, has fuel, cranks but wont start...I'm desperate

After doing the break in on my new 4.6 engine and being started numerous times after that my 2000 XJ will not start. Changed CPS tested CPS, has spark has 50 psi to fuel rail, injectors firing but it will not start. Checked and cleaned grounds as well. Could this be an ECM problem and if so how can I test for that?

Sounds like it is flooded. Put in a fresh set of plugs and give it a try.

Just did that, it hasnt started since we put the larger fuel pump in it. It has 50psi at the rail which is fine. We are going to rest ecm and if that doesnt work I am going to put old 19# injectors back in it.

I'm not too familiar with newer Xj . Sounds like a fuse, relay or the computer is not letting the injectors open.
Might try testing with some starter fluid to see if it runs then you'd know it's somewhere in the fuel supply.
Maybe swap the injector relay if it has one.

Edit: camshaft sensor?

Its getting penty of fuel. Swapped out injectors, throttle body, reset ecm . I'm stumped.

If it's got fuel and spark, timing?
I think the 2000 has a cam sensor where the distributor used to be. If the crank sensor is new maybe swap the cam.

Thinking about it our 06 jeep has a feature that keeps it from firing up if the throttle is wide open. Does the 2000 XJ have a similar feature? if so I'd find what controls that signal

Tried new cam sensor, coil pack, old injectors, old throttle body, grounds refreshed.

IMO you hit all the obvious things to check. This is puzzler. Got me curious, after doing a lot of searching it's a common problem with 2000-2001 Xj. Nobody ever followed up with a firm solution.

Suggestions include unplug o2 sensors, nss,
the odder in my mind is idle air sensor some have cleaned it or held the throttle open as they crank,
Swap ASD relay,
Check battery load below a certain level the computer will not do anything.
Fuel filter
Last I guess would be the computer.

The only thing I've seen like this was 95 civic that had a valve stuck open. Shouldn't be the case here, it was a rarity even for civics.

If it actually has spark and fuel, there is no reason for it not to run.

All the previous suggestions assume that either spark or fuel is missing, as this is the logical place to begin with no-start diagnostics. You must be overlooking something basic.

Have you physically confirmed by testing that the injectors and spark plugs are in fact firing ?

We took the coil rail off and put another set of plugs in the rail and cranked the engine. We got spark on all plugs arcing to the valve cover. Luckily I found a sympathetic parts counter guy that let me swap out the coil pack and cam sensor and return them after trying them out. So that takes care of spark. We verified 50psi at the fuel rail with gage, you can smell the fuel very noticably when you crank it over and the plugs are wet. Tried two different rails and a new set of 24#'s and the known good old set of 19# injectors. Makes no difference. So thats fuel. I have triple checked the CPS and the Cam sensor with a meter and have changed out each of these with new sensors. So that takes care of those usual suspects. Brought engine up to TDC on compression stroke and adjusted cam sensor according to instructions.
Tried old throttle body. It doesnt even act like its igniting. We pulled the jeep out of the garage and turned it around then put new fuel pump in with new regulator. Started it up a couple more times after doing cowel air intake. Then poof, it hasnt started since. Between the two of us we have worked on cars for many many years and at this point we are both stumped and dejected. Things were going so well with the new stroker engine.
Would a faulty ECM still throw spark and fuel signal?

Forgive me, as I am only a back-yard mechanic, and not a XJ Expert.

That said, I wonder if your stock ECM is an improper unit somehow for your upgraded engine, as I had the dickens to find a standby-replacement for my RENIX XJ that would properly match up, (by the OEM numbers), etc. Some had/have different bread board components/circuitry for auto, versus manual, apparently, etc. Could it be that your ECM is stock/stroker confused?

Have you googled around for any stroker hints regards ECM changes, or replacement requirements?

You mentioned cowling air intake mod. Some might have everything hooked up, and/or connected before running tests. Given your general expertise, had you, and your bud only tried to start engine with the air duct, or air cleaner box always connected? If so, check to see if there is a rag stuffed into them.

I really doubt you two have gone to that absolute length, i.e., you all must have tried to start the engine without the air duct connected to the throttle body.., hence disregard my 2 cents worth of crazy things that can happen after a few beers on such a job.

We have ran the engine both with and without the new cowel air setup. The stroker engine ran fine with this PCM just last week. Idled fine, good temps, good oil pressure, good alt output.

I want to know if it pops at all or tries to start?

Spark, fuel, AIR and something is going to happen! And the ratios can be pretty broad.

I'm trying to think when that has happened to me, spark fuel and no start or pop. Sucked a rag down the intake once. Got a load of bad fuel a few times. Leaking head gasket covered the spark plug electrodes with coolant, but even that was only two cylinders.

The only other thing I can think of is possibly a broken timing chain? Even then something is going to pop.

No pops.

The engine needs: fuel, spark, air, timing to run.
Most of the searches with solutions have something odd like O2 or TPS.

since it was running before the new fuel pump, I'd go back to that. Maybe try pulling the relay to the pump, if the engine is dry spray starting fluid and see if it does anything.
Depending on your system there may be enough pressure inline to try letting it prime, then pull the relay and crank it if it runs maybe it is getting too much fuel for whatever reason.

There is a thread where a 91 XJ was a no start had too much fuel because of a bad O2 sensor, he pulled the fuel line to test flow and it started. He also replaced every sensor but the O2, not sure how it works in the 2000 XJ I know they made it more complicated.

If it is getting proper fuel & spark at the right time you might have to look mechanical for the failure. It doesn't seem likely to me since it ran, but. It's kind of running out culprits.

BTW , Our neighbors son got the plug wires wrong on the distributor (his first car and DIYing experience.) where it'd crank and crank with no sign of popping or anything else until starting fluid was sprayed. And then there was our Honda with sticking valves, we could only eventually get that car running by holding the throttle open. None of that seems like your issues, I only mention it because you can get no start with proper fuel and spark with no popping or sputtering from the engine.

I must retract what I said earlier about it not having run since the fuel pump install. That was not correct it started and ran fine at least 4 times after that. It seems as if it is just dumping huge amounts of fuel into each cylinder. I am eager to get back under and check the O2 wires again. When we did the cam break in I actually had an innovate a/f meter on it and it was idling right at 14.7 which is dead on at idle and would richen up at 2000 rpm

Security mode or battery are two things overlooked a lot. I had 2 Durango's that came in the shop and had spark fuel and air. Slapped a new battery in and its been fine ever since. Just because it has 12v doesn't mean it has the clanking amps required. If you put a battery in, while the battery is out, touch the positive and negetive cables together to totally discharge the system then put the battery in again.

Kego814 said:

Security mode or battery are two things overlooked a lot. I had 2 Durango's that came in the shop and had spark fuel and air. Slapped a new battery in and its been fine ever since. Just because it has 12v doesn't mean it has the clanking amps required. If you put a battery in, while the battery is out, touch the positive and negetive cables together to totally discharge the system then put the battery in again.

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It cranks fine and shows 12.5 volts. I thought the computer and ignition system only required about 8 volts to function properly?

usually thats the case but some cars are real finicky about voltage and cranking amps. especially when it gets cold out. i'm not saying thats definitely the problem but i wouldnt let that go unchecked either

the COP 4.0's are pretty tolerant of low voltage. i've cranked mine over with 10V in the battery and it fired.

put a timing light on it, verify that your base timing is correct and that it's not slipped.

disconnect the fuel pump power and attempt to fire it on ether.