Can't get car to start - cranks & sparks, fuel issue?
 

So I'm pretty much at a loss at why my car isn't starting - I'm assuming it must have something to do with the fuel delivery. Over the summer for 3ish months, including a month prior where I wasn't driving the car very much at well the car sat while I did quite a bit of work and had my transmission rebuilt. When I first started it after all the work it started okay after a few seconds which was expected since it's been sitting for so long, but it ran just fine once and perfectly normal started. I probably started it a couple more times just fine after that, and then it got more and more difficult to start. The last time it started I would have to crank it, stop, let it sit a few minutes, then crank it more and it would almost catch, then I let it sit, etc until it started. Once it started it ran perfectly fine and normally - so I know the car was put together correctly and I didn't miss anything or mess something up. At this point I can't get the car started at all, no matter what.

I was thinking the fuel filter was clogged, and being pretty sure that you can't replace/clean just the fuel filter and went and bought a new fuel pump (Walbro 255lph to replace the also walbro I had). The new pump didn't fix the issue.
I've verified that the spark plugs are sparking, so it's not an electrical issue. An OBDII reader is showing RPM so the crank sensor is fine. Fuel is coming out of the pump at the pump outlet. I opened up the fuel line at the fuel rail and at first it was bone dry so I was thinking there is possible a clog in the fuel line. I blew it out as best I could and poured some isopropyl alcohol down the line to maybe clean it a bit, and after verified there is fuel being pumped through the line (though it didn't seem like it was all that much coming through?). The fuel return line is bone dry, which seems surprising since I'm cranking the car so much.
I'm not sure how the fuel pump relays on the car work. I know I 100% hear the fuel pump running and obviously I've verified fuel is coming out of the pump, so it's getting power. Is it possible one of the fuel pump replays is bad, not allowing fuel voltage to the fuel pump and resulting in not enough pressure to start the car? Again, I have no idea how the system works, so it could be possible a relay went bad? I don't hear the pump "prime" when I turn the car on, but it seems like some people say it does prime and other people say it doesn't.
There is a p0117/p0118 code as I realized a wire got ripped out of the connector, but I feel like the ECT wouldn't result in the car not starting at all, even if it would make it run rough (which again, when it was starting before it ran absolutely perfectly)

Any thoughts? I'm at a lost and almost to the point where I might get the car towed to a shop which I would hate to have to do.

Edit: Sorry, don't know why I put this in the general section and not the engine section.

Bad gas?

Put some dry gas in it and a few gallons of fresh gas

pull the return line off... then try to start it for just a millisecond.

fuel should shoot out.

or put an inline pressure gauge on the rail and do it right.
that way you can see if you got pressure or not.

The return line is bone dry. I took off the feed line and fuel is coming out of the fuel feed line itself. Nothing comes out of the return line.

I think I'm just going to pull the fuel rail off at this point and try cleaning it/the injectors. I got some of that starter spray and when I spray some into one of the vacuum lines the car starts right up for a second, so I know it's fuel related.

I put fresh gas in when it all started and it didn't seem to improve things.

ECU Needs to know the coolant temp. There is a huge difference in the amount of fuel the ECU will deliver based on the coolant temperature.

If there is no flow in the return line then no fuel.

this is correct^^^

You're right, but the car did start before even with the broken connector, so I don't think it's that.

Any thoughts on the cause of that? Could the FPR be stuck closed or something, not allowing any flow?

should be pretty easy to start taking stuff apart and figure out what is causing the flow issue.

I took everything apart and no obvious signs of something wrong. It could be the injectors clogged/not working, but that wouldn't explain why the return line isn't returning anything. It could be the FPR not working, but wouldn't the fuel rail still be full of gas and allowing the car to start? Maybe it's just both?

Just not sure what move to make next. Again not sure if the 3rd relay could be bad which isn't allowing full voltage to the pump and not allowing full fuel pressure? The pump doesn't seem to prime or turn on when I turn the key to 'on' before starting, so maybe that's the issue?

Just to clarify.
You take fuel delivery line off at rail, engage pump and it spews gas? Correct?
Then you reconnect fuel delivery to rail, remove return line, engage pump and nothing? Correct?
I dunno what to do exactly but it seemed like maybe you guys are a little murky on who's done what to where and how to proceed. But if above is on point then it gotta be rail or FPR, right? FPR does not actually block rail, right?

take the supply line off - turn on the pump... see if fuel comes out.
If yes then:
take off return from regulator - turn on pump... see if fuel comes out.
if no... then you know its the regulator


the fuel rail is flow through.
injectors being clogged with have nothing to do with not getting fuel to the return side.

Exactly

I'll double check gas comes out without the regulator, but would the bad regulator stop fuel from the injectors? Again, just trying to understand the system. Either way I'll check.

if the regulator was messed up and wasnt allowing fuel to flow thru it, it would cause the pressure to be way to high.... cause there is no "regulation" of the fuel pressure.

which would make the car really rich and it wouldnt run.