Intermittent spark

[flufrooster]

I have a 1991 4.0 Comanche that has a 88 Cherokee motor swap.  When it was swapped everything on the old 91 was put on the 88.  Now it won't start.  We changed the computer, dizzy, cap and rotor, wires, tried two new cranks sensors and flexplate.  It will crank but not fire.  The spark goes

snap snap         snap snap        snap snap.  Anyone have any ideas why it won't spark like it should?

[gogmorgo]

If you're using the flexplate for an '88, it won't work with the '91. You need one that matches the electronics, so if you've got the HO computer and everything for a '91, use a flexplate for a '91, but if you're running Renix electronics, you'll need the Renix flexplate.

 

Another member on here a long while ago was having issues with new flexplates not having windows in the correct spots, but I don't remember if it was for Renix or HO. I replaced my cracked flexplate in March with a cheap one from RockAuto that worked perfectly in my '91.

 

It might not do you much good if the motor's never been started, but have you tried checking for codes?

[flufrooster]

It has the 91 flex plate in it.  We haven't checked codes.  It has everything that came off the 91 motor.

[HOrnbrod]

Double check your distributor indexing. No matter how many times I pull one, I always find a way to slide it in wrong the first time. Here's a pretty good guide:  http://tomasz.korwel.net/2006/12/19/replacing-ignition-distributor-in-jeeps-40l-engines/

 

Where are you checking your spark? Off the coil, or at the spark plug?

[flufrooster]

Off the coil

[HOrnbrod]

Try it at a spark plug or two.

[flufrooster]

We have tested it all over the place.  lol 

[cruiser54]

Index the distributor.

[flufrooster]

I'm done messing with the thing, posted it on craigslist.  Someone with more knowledge can take over. 

[cruiser54]

I'm done messing with the thing, posted it on craigslist.  Someone with more knowledge can take over. 

craigslist where? 

 

Got a link?

[flufrooster]

I am working on getting pics on the ad

http://nashville.craigslist.org/cto/4795046678.html

[Incommando]

In your list of things that you have not replaced is the coil itself. Just a few bucks off of Rock Auto. A timing light on the coil wire will show if its pulse is erratic.

[flufrooster]

Coil was replaced.