[schecterguy]

Hey, I'm stuck here, maybe someone can offer some advice?
I'm in the process of wiring in a 91 4.0 from a yj into my 95 yj, which had the 2.5. I have the 12v, ignition, and fuel pump hooked up. When I turn the key I hear the fuel pump kick on, I have pressure, and it turns over, but won't start.
What do I do!
Thanks in advance!

[havasu]

Do you have spark?

[schecterguy]

to the coil? yes

[menace2]

What computer and wiring harness are you useing? If the computer was from an automatic, you need to ground out the neutral safety switch wire to get it to fire.

[northeaster79]

did you change your fuel pump?friend of mine did all this with his and couldn't figure out why it wouldn't start.we did some reading and found you also have to use the 4.0 l fuel pump too.

[Jim93YJ]

I know someone put together a pretty complete posting of what all is involved in making the swap...Could someone point him to that thread??

EDIT: I do not know if this will help but a searched 4.0l swap and came across this thread. Maybe this thread and some others like it have some answers.

http://www.jeepforum.com/forum/f12/4-0-swap-information-537763/?highlight=4.0l+swap

[Maloppa]

I did the same swap and just unplugged my 2.5 harness from the tub and plugged in the 4.o. I have power and all gauges work, but no power to the starter. I am going to finish the clutch and transfer case hookups to make sure that any safety mechanisms aren't causing this. Is the fuse box inside the 2.5 and 4.o the same. I would think they are but wiring isn't my strong point either.

[schecterguy]

Originally Posted by menace2

What computer and wiring harness are you useing? If the computer was from an automatic, you need to ground out the neutral safety switch wire to get it to fire.

I'm using the computer and harness from the 4.0, which is manual.

Originally Posted by northeaster79

did you change your fuel pump?friend of mine did all this with his and couldn't figure out why it wouldn't start.we did some reading and found you also have to use the 4.0 l fuel pump too.

I didn't think of that, but I have pressure at the fuel rail, it should at least start for a second.

Originally Posted by Jim93YJ

I know someone put together a pretty complete posting of what all is involved in making the swap...Could someone point him to that thread??

EDIT: I do not know if this will help but a searched 4.0l swap and came across this thread. Maybe this thread and some others like it have some answers.

http://www.jeepforum.com/forum/f12/4-0-swap-information-537763/?highlight=4.0l+swap

thanks, i've been through all of those, and the only one that has a yj to yj conversion has almost nothing about wiring.


this is going to be a long day.

[Tomb Raider]

This might help



http://www.jeepforum.com/forum/f12/2-5l-4-0l-swap-wiring-101-a-590994/



You said you have spark to the coil.......do you have spark at the plug wire ends?


Make sure your crank position sensor is hooked up. It's a itsy bitsy connection, and some CPS connections were different from year to year I found out. You may have thought it was something else you didn't need to hook it up since the connections were different. Ask me how I know The CPS is on the bellhousing on the drivers side. Thin strap of wires (three) that go up and connect into your wiring harness near the fuel rail on the drivers side.

No, you don't have to change the fuel pump. The above mention of this was probably due to someone using a 4.0L from an earlier cherokee with the renix system...of which yes, you have to change the fuel pump.

[Tomb Raider]

Another thing to do.....



Hook up your check engine light. Then get the codes from it. No codes = start. I guarantee, if you have a no start situation...your gonna have an engine code. The computer does the work...and it know's when something isn't right.

[schecterguy]

Originally Posted by Tomb Raider

Make sure your crank position sensor is hooked up. It's a itsy bitsy connection, and some CPS connections were different from year to year I found out. You may have thought it was something else you didn't need to hook it up since the connections were different. Ask me how I know The CPS is on the bellhousing on the drivers side. Thin strap of wires (three) that go up and connect into your wiring harness near the fuel rail on the drivers side.

I actually didn't disconnect any wiring from the 4.0 when I did the swap, I just moved it out of the way of the chain I used, and it was running five minutes before I started pulling it out. Maybe I'm not understanding something, am I supposed to be using the cps from my 2.5?

[Tomb Raider]

Originally Posted by schecterguy

I actually didn't disconnect any wiring from the 4.0 when I did the swap, I just moved it out of the way of the chain I used, and it was running five minutes before I started pulling it out. Maybe I'm not understanding something, am I supposed to be using the cps from my 2.5?

So, your using an AX15 tranny I assume....assuming you pulled the whole driveline from a donor YJ?


It sounds like you need to hook up your check engine light to get the engine codes. You also didn't say, do you have spark to at the plugs? No, the CPS from the 4.0 is what you need.

[schecterguy]

Yeah, I have the entire driveline from the yj. I do have spark at the plugs, so I definitely need to hook up the check engine light, I'll try to figure out which wire that is.
Thanks a lot

[Tomb Raider]

EDIT:


Black with pink stripe is the check engine wire coming from your light on the dash. I'd take a stab and say it's the same on the 4.0L.





EDIT #2: Yes, it should be the same. 20g black with pink stripe wire on the engine wiring harness that goes to the bulkhead.

[Maloppa]

schecterguy,
How did you hook up the ignition wire?