Truck won't start
 

So my sister recently had her transmission replaced in her 1996 Ram 1500, everything is hooked up as it was prior to the new transmission theres just one problem.. It WILL NOT start. It turns over but will not start and run. There appears to be no spark BUT nearly every common item to replace has already been replaced. This included (But not limited to) the starter, the coil, distributor, crank sensor, fuses, and it even has a new battery. We thought it might be the PCM so we ordered a new one, and once it was hooked up it still wouldn't start. HOWEVER with the new PCM, the fuel pump only ran for 2-3 seconds. The old PCM would run the fuel pump continuously when the key was in the run/on position. Other than that there were no noticeable differences. Does anyone have any idea of what could be causing the engine to not start now that there's a new transmission?!

Any help is good help :D

EDIT/UPDATE: After help from you guys here, we got it running and found that the transmission was stuck in first gear (Repair mistake lol). So we got the transmission fixed (As far as we know) but when we went to go drive it again, it ran for a couple of seconds (over 30), and then it died, and we havent been able to start it since. We assumed it was a fuel problem, so my dad replaced the fuel pump; still wouldn't start. So then he went out and got ANOTHER new PCM, and it is doing exactly what it did before, keeping the fuel pump running constantly when the key is in the on position. Not sure what could be at fault this time... Any suggestions/ideas?

try to start it in neutral.

You didn't get a auto zone crank sensor did u

I tried that earlier and no dice.

No, My dad has been a manager at O'reillys for YEARS, and he's very particular about the parts and companies he buys from.

What about fuel pressure ?

Our trucks seem to work best with the OEM Crank Sensor. Might give that a try.

Check for pinched wires between the engine and trans.

Fuel pump should run for about 3 seconds when you first turn the key on, then stop. PCM won't energize it again until you cycle the ignition off, or, it sees the engine turning. (crank sensor) If the fuel pump doesn't kick back on when you crank the engine, then the PCM isn't seeing crank sensor signal.

So if it is continuously running from the time you turn the key to the run position, there is a problem with the PCM? What would cause it to run non-stop? As far as I know, no wires are pinched either. Also, the problem shouldn't be with fuel pressure or the like, as the spark plugs simply aren't sparking, as confirmed with the general screwdriver test.

PCM controls the fuel pump relay. It will energize it for a 'prime', when you first turn the ignition on, but, if the PCM doesn't see the engine turning, it will turn it off. (safety feature) It also cuts power to various other system. (chiefly, the coil, and injectors.) If the fuel pump continues to run, there is indeed a fault somewhere... either the relay itself, or the PCM.

I know you replace the PCM, but, just because it is 'new', does NOT imply that it WORKS.

Grab a friend, and a multimeter, or test light. Park said friend in drivers seat, have him/her crank the engine, while you explore for power. Test the coil feed, and a couple injectors. See if you have power there while the engine is cranking. (I am going to guess "no".)

Well when we did place the new PCM in, the fuel pump oddity was fixed, but it would still not fire, so my dad assumed that was not a factor and put the old one back in. Of course at this time, I hadnt figured out that the battery was bad, and may have not had enough total power to fire it up. I advised them to put the PCM back in and try it once again, and also to pull codes using the new PCM, because it was giving a no communication error when trying to pull codes on the old one.

As for the multimeter test, my dads done a number of them, showing no power to the coil when its cranked.. And he did notice that when doing some tests when the key was turned into the on position, it would read 12Vs in some areas like it is supposed to, but only for a very short time, after that it would jump back down to 0.