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Old 02-21-2012, 11:53 PM   #1
Join Date: Feb 2012
Posts: 4
won't start after replace 2.5 Engine

I'm hoping for a little help with a frustrating problem...

I just replaced my 88 yj 2.5L engine with a 93 2.5L YJ engine but the engine won't start unless I pour gas or spray choke cleaner in the throttle body. The original motor ran fine but smoked extremely bad. I am using everything original from the 88 engine including the flywheel. I have double checked the crank position sensor and it is connected. I can see fuel hitting the throttle plate when I crank the motor and it fires the plugs fine. I checked the pressure from the fuel pump and it is slightly above 15 which should be ok. I dropped the tank to check the rubber hose and the fuel pump was rusted so I replaced it hoping to avoid problems down the road. New fuel filter as well. Blew out all the fuel lines with an air hose and they seem to be clear. I did notice that TDC on #1 doesn't match up with the #1 labeled position on the distributor cap, it's 90 degrees off. I have the 93 distributor and when I checked the rotor alignment to the distributor shaft bottom flat part it is 90 degrees off from the 88's. Anyone know if there is something that has to be done to get this motor to start.

sorry for the long winded explanation.


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Old 02-22-2012, 06:42 AM   #2
Join Date: Aug 2011
Location: Central Maine
Posts: 274
Is the '88 distributor in the motor or the '93? Are you sure you're on TDC on the compression stroke? Can you get the distributor to align to #1 plug at TDC?

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Old 02-22-2012, 07:32 AM   #3
Join Date: Feb 2012
Posts: 4
Currently it has the 88 distributor in it. I haven't checked how close it ls to TDC. But it runs if I pour fuel down the TB. Could timing cause it not to start unless I add extra fuel?
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Old 02-22-2012, 08:00 AM   #4
Join Date: Aug 2011
Location: Central Maine
Posts: 274
If the timing is off it shouldn't start even when you add fuel to the TB. Does it stay running after you prime it or just die as soon as you stop dumping in fuel? Any chance you have the supply and return lines reversed?
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Old 02-22-2012, 01:12 PM   #5
Join Date: Jan 2010
Location: Las Cruces, NM
Posts: 2,291
You might want to check with someone familiar with engine swaps cause I don't think you can do what you did. the 93 was fuel injected and I would think would have a different cam in it along with the crank sensor etc. Just my thought on it...
(Sold)1994 Jeep Wrangler 2.5L, Bestop top
/w steel half door and slider windows
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Old 02-23-2012, 08:18 PM   #6
Join Date: Feb 2012
Posts: 4
It was the fuel lines were backwards at the TB. I swapped them before but it didn't make a difference. Now I realize I had the #1 plug wire in the wrong spot on the distributor cap. Thanks for pointing out my mistake... Now i'm running....

I am curious about the cam though. I'm going to check on that.

thank you!

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Old 02-23-2012, 08:26 PM   #7
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Location: Asheville, NC
Posts: 357
Good call Brent!
'95 YJ 2.5L, 5-sp, 2.5" lift, 31" Pro Comp MT's

'62 Willys pickup Super Hurricane L6
Original, disassembled and in slow progress.
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Old 02-24-2012, 06:58 AM   #8
Join Date: Aug 2011
Location: Central Maine
Posts: 274
Glad to hear it's running! Your cam should be fine, you did the critical part of the swap...putting your '88 flywheel on the '93 block.

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