Okay, so I tried starting my car today for the first time. It starts, runs for a couple seconds then dies. The amount of time it "runs" is not consistent. Working the gas pedal doesn't seem to have any effect.

I have good fuel pressure at the rail- with key on it is 12-14 PSI and it climbs for the short time that the motor is running.

I double checked that we have the spark plug wires routed correctly. Distributor was never removed, so it should be fine.

This is the set up:
Out of a 1994 Jeep Grand Cherokee (OBD I). Ran great in the Jeep. Using the Jeep relay/fuse box. Everything is stock for the Jeep. I have removed all the EGR and Evap equipment.
Neutral safety is grounded at the computer. I have one wire hot to the computer all the time, one wire hot on key on.
I tried to check codes using the CEL wire off the PCM, but it doesn't light my test light and my voltmeter doesn't move enough to discern how many times it's flashing.
I had heard that the ignition switch has a dead spot between start and run that the PCM does not like, so I wired in a start button so it would not cause an issue.
Jeep had an auto, I swapped in a 5-speed. I put in the correct V8 flywheel and had to change the crank sensor to a manual shift sensor. The two sensors had differing wiring connectors, so I swapped the connectors. Not sure if this may be incorrect.

Not sure what else to look at. I've heard that the Jeep's have a security feature that needs to be disabled. I'm going to start searching for that, but does anyone have anything I should look at first?

Any help is greatly appreciated.

-Dave

12-14 PSI is not good for MPI.

12-14 is too low but I think you have a different problem also... Those jeep computers have a security thing in them where you can not break a window hot wire it and take off. If you lock the door with the key out of the ignition the BCM tells the engine and it will start then shut off. If you unhook the power you can (and usually do) trip the alarm, you try to start the jeep and it starts for a second or two and shuts off. The only way to disarm it is to lock all the doors and hatch and unlock the door with the key in the door or with the factory remote, then the BCM tells the ECU it is OK to start and keep running. To retrofit all the BCM and door locks into the old car is a massive undertaking. The easiest way to fix it is find a V8 magnum OBD1 dakota, van, ram and use the computer from it, auto or manual will be fine. It should plug in and work with the wiring you have.

The dodge stuff did not use that type security till 97-99, in 2000+ you need the grey key programed to match your computers vin.

Okay, did some more poking around today. Pulled all the plugs. Each plug smelled of gas.
I then checked for spark at each plug and this is where it was weird. I had spark, but not a consistent bright spark. It would alternate between bright and dim spark randomly. Not sure what controls the strength of the spark other than the coil.

Any ideas on what I should check next?

Non consistent spark would definitely cause what I was seeing yesterday.

Thanks.

that's right... on my dads jeep, there was a wire you can ground that tells the BCM/ECM that everything is fine. He was getting highly annoyed at the security system, so we disabled it.

But I believe it only works to ground the wire if it's currently in 'ok to run' mode.

So I guess in theory, if you can disarm the system, then figure out which wire to ground, it should be good forever.

What PSI should they have in the fuel rail? I'd think 30+?

Dave, I have done this swap. I swapped a magnum 5.2 into my carbed 88 Jeep using a 1995 jeep grand cherokee OBD-1 harness/ecu. I used a 5.2 out of a 99 Dakota, but used the 95 jeep harness/sensors/injectors/ecu because OBD-1 is much easier to deal with. I also used a 5 speed manual trans where both donors were autos.

First and foremost, the Grand Cherokees have a built in security feature, as has been mentioned already. Mine did the same thing as yours is doing. It would fire, run for a second and quit. You will have to replace the ECU, there's no getting around this. For around 40 bucks online I got an ECU out of a manual trans 5.2 Ram. The Jeep ECU is useless to us. After swapping this out, she fired right up and purred like a kitten.

Secondly, a simple 12v test light works for checking codes. That's how I checked for codes until I wired in a permanent in-dash light.

Thirdly, your starter switch you wired in, remove it. Mine lights off the key just fine.

I also had the issue with the crank sensors. I just changed the pigtails on the sensors after buying the manual trans crank sensor and problem solved.

What are you using for a fuel pressure regulator? I never checked the fuel pressure on mine, but I've read these things are looking for around 50psi.