1998 GC Laredo, 4.0L, Auto, 4WD

I'm new to the forum, having just purchased my first Jeep. Have searched for a couple days, but havent really found another post that matches my issues.

Short history - I bought and drove this GC for a couple days and then ended up with a rod out the side of the block. I rebuilt an engine from a 97 GC (so I was told). In the rebuild, I also replaced ckps, coil/cap/rotor/wires/plugs, fuel pump and battery.

Now, it cranks but will not fire. I've been chasing +/-/ohms to make sure wires and things are where they're supposed to be. In doing so I discovered continuity between + & - battery cables (1 ohm). Which explains why the new battery drained quickly and went bad after just a day or two. I've unplugged all the sensors and fuel pump, all the ecm plugs, pulled under hood fuses & relays, and took off block grounds. I cannot make the short go away.

What am I missing? I know its something stupid, but I'm out of ideas. Thanks!

 

Shorts blow fuses and burn wires. You have a parasitic draw somewhere.

https://www.youtube.com/results?sear...itic+draw+test

 

Cant truly trust an ohm meter to test between battery cables, If you had 1 ohm there you would instantly be on fire and blow up the battery. What its reading is stray capacitor voltage from the pcm.
Your problem is crank but no start. I'm suspicious that it's a 98 and you put in an unknown engine year. I do know 98 was different from 96-7, which was different again from pre 96. Might make a difference with the crankshaft sensor triggers placement on the flywheel and with the indexing of the cam sensor. Just a couple things to consider before starting.
That said I actually don't know, because I wasn't the mechanic and didn't check. But if I was, I would have. You were. The mech is responsible to check.
with the key on engine off, do you have 5VDC on the sensors and 12VDC on the IAC motor?

 

I say that i think I have a short because i have ruined 2 new batteries in trying to get this thing started. Have heard shorts and parasitic drains are a common in these vehicles. Where have you guys found them? I know I'm missing I'm something easy

 

If it hasn't fired up since it's been rebuilt, there's a good chance something wasn't installed properly or the wrong part was used. The original flexplate should always be used unless it got damaged because the sensor windows that trigger the crank sensor must be located properly for the system being used.

 

Simple fix. Just pull the engine and start over,

 

I was hoping it wouldn't come to that!

Was wondering about that though. I had to use the crank from the 97 block, but used the flex plate from the 98. Is it possible that the 97 crank is indexed differently and with the 98 plate its screwing things up? Thought I read before I started that 97-98 were interchangeable and 96-ealier and 99-later were different.

 

An ounce of prevention is worth a pound of cure. This is where doing your due diligence before hand counts. I do not know the interchangeability but I do know if I was doing what you were doing, I would know, and before I did it.
You indicated you were only TOLD it was a 1997 , did you check? Did the crank look the same?