Engine replacement

This is a good one. I have a 95 XJ, 2 door, 5 speed, 4.0. After 280,000 miles the motor finally gives up. I decide it is time for a new engine. I buy one and pull the old one out with the wiring harness still in tact but unplugged. I pull all of the wiring off of the old engine and all of the amenities. ie oil sending unit distributor and coil and so on. I put all of this on the new engine. I put the engine back in and plug everything back in. I go to try to start it and nothing. I check all of the wiring, it is all good. I can get the engine to turn over if I hook a wire from the batery to the solenoid to jump it. The fuel pump will not run because it starts off of the starter relay. I am trying to go thru the wiring diagram but the haynes book is real vague and I don't have a yellow and brown wire into or out of the ECM. Any ideas, I am out.

i had a similar problem when i swapped my engine and it ended up that i broke my CPS when installing my newer engine so i replaced that and it started up. i hope this helps.
-mike

No one out there has had this problem? I can't get power to the starter relay through the key switch and it was working just before I pulled the engine and replaced. Is there anything I should check?

CPS, and recheck all your wiring, unplug it all and then plug it all back in. Then check your ground straps.

What made you decide on the new engine? Possibly an extra problem going on there

Yeah--How did your motor give up? Did you hear internal parts go bad or did it just not start up one day and you swapped in another engine that inherited the no start symptom?

I was driving it and it blew all of the antifreeze out and before I had a chance to get it over it was done. I tried to start it when I put it on the trailer it would turn over but it wouldn't start. Tried to start it when I pulled it down the driveway, it would turn over but would not start. sounded like no compression on about 4 cylinders, but it would turn over with the key switch. Replaced engine within 2 days now it won't turn over with the key.

If it ain't the CPS then it is a ground or actualy the lack of one. IMHO

Thanks to all that answered. I found a ground that was not completely tight. soon as I tightened it, it fired up. Must have got some moisture in it. What is the best way to get water out. I am going to try to pour some kerosene down it and keep flushing it. The engine sounds good.

Heat will remove the moisture, new cheap oil, run it and let it heat up, the moisture will be removed via the CCV system or is supposed to but heat and the oil getting hot will cook it off.

My stroker would not catch till I changed out the ground straps, it would spin and spin but never catch. As soon as I changed to a new ground strap it fired right up

If you want to get moisture out of your grounding points then use a wire brush and some solvent (PB Blaster) then pack them with regular grease. You can use dielectric grease too but for grounding points where there are no other signal wires anywhere around good old regular grease works better since it's conductive. It will all wash out in a few months anyway but it can prevent rapid corrosion.