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Unread 12-12-2011, 03:48 PM   #1
gkinder
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90 to a 95 block swap.

Hey all, great site with a ton of info!

I recently purchase a 1990 yj with a 2.5 that had really bad blow by. I almost wanted to hook a whistle up to the oil cap just to hear the tune it would play.

I found a 1995 2.5 out of a wrangler for dirt cheap, and always wanted to try my hand at a rebuild. All seemed to go well, it turned out this newer engine had already been rebuilt. I didn't touch the cam, crank or timing chain. Replaced the rod bearings and oil pump closed her up and swapped all my 90's parts onto it.

I read somewhere that the 90 flywheel and the 95 were not interchangeable so I bought a new 95 flywheel. It looked identical to the 90. Regardless I installed it, dropped the engine in. Everything hooked right up with no issues.

Problem is there is no fuel whatsoever entering the intake. 20 seconds bursts of trying to start it 4 times with a little rest in between and the intake is bone dry. I am thinking I may have made a mistake using the newer flywheel because the crank position sensor is also different between 90 and 95.

Any suggestions?

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Unread 12-12-2011, 04:00 PM   #2
moonshinefuel
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The flywheel story is a bit confusing. Your original idea of simply swapping everything over to the new engine was a great idea, including the flywheel.
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Unread 12-12-2011, 04:04 PM   #3
moonshinefuel
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Maybe its nothing to do with the flywheel as you stated they looked identical. If the crank sensor notches were the same, then you should be good there. Seems like you may just have a fuel delivery problem unrelated to the flywheel.
If the crank sensor notches were located differently, then that's a problem.
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Unread 12-12-2011, 06:19 PM   #4
gkinder
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Just got a second pair of hands to help me and there is no spark either. There's a ton of things to check now so first thing in the morning I'll be back under there.
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Unread 12-13-2011, 08:31 AM   #5
gkinder
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Today I will begin removing the engine to swap the flywheel back to the original. I hate that I have to do it but it was a great learning experience as far as crank position sensors go. I come from a different time when these sort of sensors didn't exist.
When I said the flywheels looked identical I was referring to the teeth and diameter. I didn't realize that the monster plate attached to the flywheel was something that needed attention. The 90 flywheel reads 12 notches before TDC and the 95 reads 4 notches to determine TDC.

Fingers Crossed.
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Unread 12-13-2011, 11:49 AM   #6
moonshinefuel
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Theres no question that if the crank sensor notches are wrong on the flywheel for your jeep, you will not be going anywhere with it. It wont work. You can just pull the transmission out, probably not necessary to pull the whole engine again, unless its easier for you to do it that way.
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Unread 12-13-2011, 11:59 AM   #7
Que89YJ
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Welcome to the forum!

Yep, you needed the 90 fly wheel to sequence the crank sensor correctly. The 90 is a TBI so you are dealing with 1 injector, when the 95 is MPFI so you are syncing 4 injectors. The crank sensor is used for injector pulses.....but I guess you figured it out before MSF and I posted.
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Unread 12-13-2011, 12:34 PM   #8
gkinder
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I just disconnected the starter remove the motor mounts and some of the vacuum lines that didn't have a lot of stretching room and parted the engine and trans enough to drop the flywheel out... Now just need to wait till I get a second pair of hands to hold the crank still to get the flywheel off.
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Unread 12-14-2011, 02:23 PM   #9
gkinder
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She's 100% now! Switched the flywheel back to the 90 and it fired right up!
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Unread 12-14-2011, 02:25 PM   #10
Schaef81
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Good work! I made the exact same mistake when I swapped engines. It was a big slap in the face at the end because swapping flywheels while the engine is out is a 5 minute job.
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Unread 12-25-2013, 09:25 PM   #11
stumped6869
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o crap looks like im pulling mine also I figured as much when I had no spark after testing the cps ohms errrrrrrr here I go again five minutes would have been great over few hour job lol
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