Did an engine swap this weekend into my 99 WJ 4.7l. Last night we hooked everything up (at least we thought) and it wouldn't start. It was the Crankshaft position sensor wasn't plugged in. Then it started up and ran for a minute or so until we purposefully shut it off. We ran it without any exhaust hooked up. This morning we went to go start it and it wouldn't. The voltmeter reads 9 volts even though the battery is fully charged. The gas gauge reads completely empty even though there's 1/4 tank in it. The key light is on. I tried the ignition trick to get the error code and it didn't work. The starter cranks but it's getting no fuel. We have checked every fuse in the Jeep. Swapped the PCM from the donor vehicle, still had same error. Rechecked some grounds. (Think they're in the right place) and still had the same problem. Tried hooking it up to a different battery, didn't work. Checked the battery connections, ran power directly to the fuse block and fuses. Swapped the relays for the "important" ones in the underhood fuse block.
From what i've read it could be the PCM (unlikely because i tried both). The crankshaft position sensor was what caused it to not work originally and it threw a code, so i'm weary to believe that's what it is. We tried putting jumper cables in different places as grounds. I'm really stuck as to what it could be so any help would be great. It's starting to be really frustrating.
Ground to the engine block, not "the body and frame at the same time" as there is no frame.
Take your jumper cables, and hook one from the negative terminal of the battery to the block somewhere, and hook one to an existing ground wire on the body.
You can't use the PCM from another WJ without programming the VIN into it, for it to talk to the TCM and the BCM.
Pull the battery cable for a few minutes, Put the original PCM in, jumper the negative to the block, and try again.
BTW, this was a Mopar CPS not a part-store brand right?
The major grounds to the engine block are there, and we have hooked the jumper cables multiple times from the negative terminal of the battery to the block/and on the unibody in multipl places. The PCM from the other WJ was just a test after it stopped running as I had read about PCM problems that caused similar issues, so it was worth a try. The original PCM is in there now. We have tried pulling the battery cables. Installed new terminal connectors on it as well. The crankshaft position sensor is the stock one. It was disconnected at first and it wouldn't run because of it, but when we connected it, it ran fine until we shut it off. I will buy a new one just to double check and make sure it is ok.
How was it running when it was running? Did any codes come up? What year engine did you use? Is it cranking over and not starting or doing nothing when trying to start it?
It ran fine when running. I was actually really surprised at how well it was running for the donor vehicle having been sitting for almost a year and mine sitting without a motor for almost two years. The only code that came up was for the crankshaft position sensor, and that was before it was running, and when it was unplugged. It is cranking over but not starting. The engine is also from a 1999 WJ.
I would check to see if you have a ground at the crank sensor on the factory harness plug. Then see if you have a 5 volts reference signal. The third spot will be a voltage that goes up and down from 0 to 5 volts. The factory plug will have three terminals the middle is ground the two out side ones are the signal and reference volts.
If the factory harness plug reads 5v and a good ground and shows a voltage the goes up and down, then your wiring is fine to your plug and more than likely it's your crank sensor or tonewheel thats bad.
If your crank sensor and factory plug test out to be good then it could be your ads relay or your cam sensor or your cam tonewheel could be damaged or bad. Or maybe your fuel pump is bad, unscrew the relief valve and push in the little plunger and see if fuel squirts out, if fuel squirts out you should have enough fuel pressure. Another thing you could check is take off your fuel filter and see if you can blow threw it, if it's really hard to blow threw you might as well replace it.
If your engine is cranking but not starting then that means it's either fuel or spark or your timing is off.
What is the code that came up was it a p1391?
i forget what the exact code was offhand, but it said it was the crankshaft position sensor when i looked up the number. it won't even say done on the dash doing the key on/off three times anymore when it starts "acting up" the dash goes to 9 volts and i'm pretty sure no power goes to the fuel pump at all because it says that the tank is completely empty but during the 5min of run time it said there was 1/3 of a tank (the fresh gas we poured in it). I mean i guess there's no harm in buying a new crankshaft position sensor, and fuel filter and changing those out to make sure. The next step I was going to try was completely pulling the harness and checking the connections to make sure theres no wires that have a weak connection or break in them. That's our last resort, but I can't think of anything else right now.