Help Please - 74 1.8 L Jet Issues, Either missing on #4 or won't start at all Options

[SteveL]

Basic Info:
74 1.8 L-Jet
Just installed new SMP injectors
Fuel pressure gauge installed.

I installed new injectors on 1 & 2 yesterday to replace a leaking injector, and it ran really nice after - better than before, leading me to believe that the old injects weren't 100%.
So, today I installed the other 2 new injectors on # 3 & 4 on passenger side. Now won't start at all. Fuel pressure gauge shows 36. I checked all fuel lines, all injector connectors, all vacuum lines. All looks good. Still no start. Time to step away, go get lunch.
Hour later, try again - she starts but backfiring really bad through exhaust. Check all vacuum lines again, all look good. Start it again, starts good, but is running rough. Idle is way high, adjust idle screw as it warms up to get idle down to 900. I think I may need a new cold start valve. Once warm, steady idle at 900. give it a little gas, and hold steady around 2700 rpm and it backfires through exhaust. To see if a specific cylinder is missing, I unplug wires one at a time. Pulling #4 makes no difference. #4 isn't firing.
Plenty of spark at the wire. I THINK the fuel injector plug tested ok. Took out injector and pointed it into a bottle. Had the lovely wife crank it over, no gas going into bottle.
AHA - bad injector. re-install old injector. Now no start at all. Check engine bay, and the hose on the old injector has also sprung a leak. WTF!!!!

Also, when testing the fuel injector plugs with a test light, one side was always hot, the other side would be lit with key on, then flash when engine cranked over.

Deep breath. Reinstall the new SMP injector again. No Start. Sit down at desk and throw myself on the merciful wisdom of the club.
Help me Obi-Wan Kenobi's, you're my only hope (kids are watching Star Wars in the other room...).

(IMG:style_emoticons/default/headbang.gif)

[wonkipop]

the full test for fuel pressure is to disconnect the vacuum hose from the pressure regulator. the vacuum hose is easy to get at with the aircleaner out of the way. the whole thing is easier with the aircleaner apart anyway so you stick your fingers in to operate the intake flap.

turn the ignition key to on with the intake flap pushed open. you should get 2.5 atm/35 psi.

you can do a test with the engine running if the engine runs.
let the engine idle. disconnect the vacuum hose. (sometimes easier to disconnect the vacuum hose at the intake plenum if the air cleaner is installed - though you got to get your fingers in there as well and its under another hose from memory)
should read 2.5 atm. 35 psi (a bit either side ok).
reconnect the vacuum hose, should drop to 2.0/2.1 atm. 28 psi - 30 psi.
rev the engine, pressure should rise.

if you were running the engine at idle when you read the pressure with the vacuum line in the pressure regulator, 35 psi is too high.

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i'd be testing the injectors with some swapping over of 3 and 4.
just to make sure its not the injector 4 itself. take 3 out and swap it for 4 and make sure it sprays vise versa. you can start to narrow it down to maybe something in an electrical plug connector or wiring.

it sounds like it must be a plug or connector that is loose, dirty etc.
the car ran fine before you changed the injectors?