suddenly hard to start renix 4.0 after installing fuel pressure regulator

so i replaced my fuel pressure regulator the other day on my Xj. replaced all three fuel rail quicks while i was at it. now the Xj only starts sometimes.
symptoms:
it will turn over and even fire for like 2 seconds and act like its about to start , but then it doesnt.
sometimes it starts up on the first try, sometimes ten times. each time i get crank, and a slight start up, then it dies.

im going to put the old regulator on and see if that helps. if that doesnt help ill be testing and probably replacinf the crankshaft position sensor .

ill also be verifying sparka nd proper fuel pressure as well .

anyone got any other ideas for this random no start that is like a "almost start" every time?
i am pretty sure if the NSS is going it wont even crank or even almost start, so im ruling out hte NSS , i dont need to put it in neutral

but i think a lack of fuel upon startup could do it?
maybe the brand new regulator is bad?
maybe the CPS is going out? unplug and replug didnt help.

Fuel pump has 2 different electrical paths, one for cranking one for running. Sounds like a bad ballast resistor on the drivers side fire wall, two elec. connectors, white part, or the run fuel pump relay is bad, either can cause your problem.

i swapped the regulator back in.
nothing changed.
i checked the ballast resistor on the driver side fender, that was one of the first things.
ill look into the location of the run fuel pump relay figure out how to test it...

once it is running its great. itll rev up real high when it finally starts, making me think its the TPS,
its weird how it will want to start then kinda start for half a sec, then die...

tested
tps- i set INPUT /OUTPUT ~.83
map - 5 v input and output
crankshaft position sensor-tested at 206 ohms, needs to be between 125 and 260


swapped in a few different coils
everything is the same

swapped in a few different ballast resistors
everything is the same

checked for any additional wiring issues.
couldnt find anything
it will start eventually, but itl take about 4+ times of starting right up then dying until it stays running.

pulled off some of the relays and cleaned the contacts same thing, no change.
checked o2 sensor and knock sensor wiring,
no issues

what could have happened while swapping out the fuel pressure regulator that it is doing this?
i swapped the old one back in.still doin it.

could it be the ignition switch?
could the fuel pump be going out ?
relays? which ones?
i cleaned and di electric greased all relays
i am at a loss right now

What did you touch/move when installing the FPR? Injector harness? Vac line from TB to MAP?

I'd be looking over these things before proceeding any further. Why did you replace the FPR anyway?

i pulled the vacuum harness off and reinstalled everything .
the vacuum lines where the first things i checked.
i replaced the FPR because i was having a fuel smell and noticed some fuel in the FPR vacuum line.
the smell ended up coming from a cracked filler neck vent tube,
but since i already ordered the FPR for the xj, i figured i might as well swap it in.
replacing my FPR on my 86 4runner did wonders for the idle. i figured it wouldnt hurt to replace the 89 FPR
i have triple checked all wiring to anything around the FPR. injector harness, TPS harness, CPS harness. double checked all vacuum lines, to map as well.


i am very well aware of the vacuum line to the MAP needing to be good. when i first got my XJ years ago that line was cracked and it took me a while to figure out why it ran like crap.

so far this morning before work i was able to :
swap relays
put a quick charge on the battery as well to get it up to over 13V since it was reading like 12.38.
and so far, not getting my hopes up, it starts right up everytime.
teh first relay swap didnt do anything. second one i swapped in seemed to work.
i can also hear the fuel pump priming as well so i know its working