M50 Swap possible injectors not working, won't stay running - Solved

[M3Gonz]

Hey all,

I've been searching other threads here looking for an answer and not much luck. Common theme is people not providing enough info then they disappear and I never see an answer in their thread! So here goes:

M50 obd1 swap
M50 fuel rail w/pressure regulator
vacuum line off bottom of regulator running to back of intake manifold by the intake air temp sensor
Fuel pump is working, there is plenty of fuel pressure (I know this because there was a bad leak initially in one of the fuel lines, right at the fuel rail)
Car turns over great, and it runs like a champ as long as we keep a constant supply of brake cleaner spraying into the air intake (ha!)
As far as I know we're using the correct DME, and EWS shouldn't be an issue. If EWS was an issue would it run or turn over at all? Or have fuel pressure?

I've uploaded two videos to the YouTube where you can hear it trying to run.

https://youtu.be/2mYWRDMYLvM

https://youtu.be/900HBG_BEU0

My theories are:
Does it matter which fuel line is hooked up to each end of the fuel rail? I can try switching them if it's important.
Old gas?
Vacuum lines not run correctly? Doesn't sound like it on the videos or in person
Bad solenoid/fuse?

Thanks for the advice on what to try! I'll try to provide more info if you tell me what I'm looking for. Bad news is my son and I only get to work on the car once/week at my father-in-law's machine shop, so we won't be back at it until next weekend. But hopefully I'll have a list of things to try from all you fine folks!

[M3Gonz]

Turns out the fuel lines, and which one is hooked up to either end of the fuel rail, must be important. My father-in-law didn't think it made a difference, however I asked him to go ahead and switch the two lines and it fires up and runs like a champ now. Or more accurately it fires up and idles like a champ, we'll see what happens when we hit the road.

[hoveringuy]

Yeah extremely important.

Fuel needs to enter the front of the rail and exit through the pressure regulator or no fuel!

[M3Gonz]

Yeah extremely important.

Fuel needs to enter the front of the rail and exit through the pressure regulator or no fuel!

Question: this car is a mess, we got it as a half-completed project with nothing running or hooked up. Normally how does one know which fuel line is incoming vs. return? Are they supposed to be different hoses or labeled, or is it just a wild guess?

[Northern]

If whoever pulled the old engine didn't label it, trace it from the fuel filter. Needs to go to the front of the M50 rail.
The rail needs pressure from the restriction of the FPR, so feeding fuel one way you build pressure in the rail and the other you don't.

[M3Gonz]

Makes sense. Eventually (next winter) this car will be getting S52 swapped, the M50 will come out, and at that time we'll plan on replacing a lot of the lines such as the fuel, brakes, etc.