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Unread 11-03-2011, 10:32 PM   #1
mooks73
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1994 YJ Wrangler 
 
Join Date: Nov 2011
Location: rialto, ca
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put a 4.0l into my jeep.lots of problems.

i bought this jeep from a man who was in the middle of a 4.0l transplant.he told me the jeep was originally a 4 cylinder and when the engine blew he decided to put the 4.0l.the motor is a new unit the the po bought from jeep.the motor was installed at an unknow shop but they never got it running.when i bought it it didnt have the correct 6 cylinder harnes or ecm.i bought a complete engine harness and a new ecm for the 4.0l.i noticed that the new harness would not turn the motor over and traced the ignition wire and rewired it to the correct location on the bulk head.now i got it to turn over but not start.got a code for the crank sensor,so i replaced it.now it will want to start and act like its going to start but wont.after a few attemps i got it to turn on for a few seconds and then it dies.i have spark and 40 psi of fuel.i believe it still has the original 4 cylinder fuel pump if it matters.can someone please help me figure out why i cant get it to stay running.all imput is greatly appreciate it.i know you will need more info so please take it easy on a noob and tell me what info you need or might need.

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Unread 11-03-2011, 10:42 PM   #2
94chb
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what year and model did the harness come from? is it just plugged in or is it rewired to work with your bulk head?
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Unread 11-03-2011, 10:43 PM   #3
Xpress
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FWIW the stock 4 cyl harness should plug right into the engine if it's from the same year jeep. All you gotta do is wire up the extra injectors and the likes.

If it has spark and fuel it has to fire up. I'd go through and check all of the sensors to make sure they are all functioning.. might want to pickup a Multi-meter...
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Unread 11-03-2011, 10:46 PM   #4
dodger889
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Check your cam position sensor (CPS)....
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A 89 yj with a 4.0 aw4 sye out of an 92xj. Now the hard part is done time to get it up in the air just a bit. Working on 8.8 with 3.73 and lsd for the rear. and new D30 hp with 3.73 .
For those who have not figured this out I'm old school but can handle the new too.
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im just cheap, and cheap makes you creative.
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Unread 11-03-2011, 10:54 PM   #5
mooks73
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the harness came from a 94 wrangler with a 4.0l motor in it.the only thing i rewired was the starter wire.i do own a multi meter.how do i check the cps.
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Unread 11-03-2011, 11:12 PM   #6
AaronJ
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My first thought is ignition timing. Generally a distributor is set to be in the "ballpark" range before the first start. Sometimes you have to play with the distributor a few degrees one way or the other to get the engine running.

Also, double check your firing order to make sure the plug wires are routed correctly.
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Unread 11-03-2011, 11:50 PM   #7
ratmonkey
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Theres no timing adjustment with the dist, its controlled by the ecu from the crack sensor reading.

trace out all the wiring, make sure it is all continuous and plugged in where it belongs. Make sure none of the injector or plug wires is mixed up.
Check the coil.
check the o2 sensor, if its shorted it can kill an ecu.
Verify all fuses and relays
Good battery with full charge and tight connections?
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Unread 11-04-2011, 09:30 PM   #8
mooks73
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rat monkey is correct.the distributor is non adjustable,but it doesnt mean its installed correctly.can anyone show me the correct way to install the distributor.i have tripled checked all connections and even replaced the harnes twice and it still has the same problem.i also changed the cps and still nothing.it wants to start but just wont stay running.i will make sure to replace the battery post tmrw and see if that helps.thanks for all you help.
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Unread 11-04-2011, 10:08 PM   #9
dodger889
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If it's trying to start that would mean that the timing is somewhere close. the easy thing to do is to bring #1 cylinder to tdc on the compression stroke. and see where the rotor is pointing should be very close to the number one plug wire is. Have you checked the fuel pressure yet? I would almost say that you do not have enough fuel going to keep the engine running. Here might be a trick to try jumper the fuel relay socket from pin 30 to 87see if runs.
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A 89 yj with a 4.0 aw4 sye out of an 92xj. Now the hard part is done time to get it up in the air just a bit. Working on 8.8 with 3.73 and lsd for the rear. and new D30 hp with 3.73 .
For those who have not figured this out I'm old school but can handle the new too.
Quote:
Originally Posted by bigsquat View Post
im just cheap, and cheap makes you creative.
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Unread 11-04-2011, 10:44 PM   #10
mooks73
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the fuel pressure stays solid at about 36 psi.i will comfirm this tmrw.
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