Motor Swap - no start

I'm about to lose my mind... i've checked everything I can think of, but this motor just will not start. It stumbles when being given gas while cranking, and almost goes on its own but is off just a tiny bit and will not stay cranked.

So far I've rang every wire out that I can think of. All injectors ring both back to the Power distribution center and the ECM, the coil wire rings to the PDC, all battery leads and grounds ring out to the ECM. The spark plugs (new) are gapped to 35 thousandths, rotor button, cap, and wires are new to go with the motor swap. I have replaced the crank and cam position sensor in a desperate try at making the issue go away. Fuel pressure is reading 42 psi at the rail.

About the only interesting fact is the ASD relay will operate and then shut off again. Power (when not cranking) is at the coil and injectors for about half a second and then disappears. What would cause this symptom?

Other items of note, this is a stroker motor from ATK going in a 98 xj. Did the flexplate change slightly somewhere to throw my timing off? Like I said, I'm lost. I'm gonna grab a new 'puter in a bit and plug it in along with some injectors... I'm assuming nothing is really going to change. Anyone got any further insight?

Was the distributor out of this motor? You may have an indexing problem with the distributor.

Just came back to add that. I am using #3 to set the timing. When #3 is at TDC the button is pointing directly at the pole on the cap. I know everyone goes to #1 TDC, but is it a special pole or will any terminal do the trick as long as the button and TDC line up??

I would do it to #1, when we did my engine swap we had a hell of a time getting the oil pump key way lined up right.

gte636p said:

Other items of note, this is a stroker motor from ATK going in a 98 xj. Did the flexplate change slightly somewhere to throw my timing off?

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flex plates are the same 91-98 what year did yours come from?

I'll bet your distributor is not indexed correctly. That's the problem in 99% of the "I just swapped motors and it won't start" threads.

gte636p said:

Just came back to add that. I am using #3 to set the timing. When #3 is at TDC the button is pointing directly at the pole on the cap. I know everyone goes to #1 TDC, but is it a special pole or will any terminal do the trick as long as the button and TDC line up??

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I think you need to revisit your manual for setting the timing. It's number 1, not number 3. Also critical is TDC on compression stroke, not exhaust.

Timing has been verified on TDC #1 (compression stroke). It's really the same as setting it to any other cylinder on TDC, compression, assuming the motor is an even fire setup.

Either way, it's still stumbling and not starting. Anyone got any other ideas? It really does seem like a timing issue from all the CJs I've played around with. Perhaps it's running a bit lean without the 24lb injectors... but it should at least crank up correct??

It tries to go when I give it some gas while cranking, but that's really no different from the computer needing to reset itself here and there in the past. When that happens you just hold ~ 2k rpm for a minute or so and it relearns things. Am i fighting this??

Too many questions right now.

Casting numbers confirm that both blocks are from 91-97. That rules out a change in flaxplate alignment doesn't it? Can you install a flexplate wrong? Will the bolt holes line up??


Forgot to add:
Confirmed spark with timing gun. All grounds have been replaced with -0- gauge welding wire with lugs soldered on the end. There are currently three, one to the flange of the starter, another to the head, and a third to the unibody right beside the battery. All positive battery leads have been replaced with the same wire. Currently I have on lead going to the starter, the PDC, and the alternator. If I have any of these hooked to the wrong location maybe it could cause some issues?? Everything worked fine before the swap, just replacing a tired motor with 260k on the clock.

I stand corrected. I would have argued this umpteen times, but it seems that I don't know how to install a distributor. The manual I had showed #1 at ~7 o'clock. After confirming many times that at TDC #1 I had the button pointing to 7 o'clock and reading everyone's insistence that it was the distributor (and that was the only thing that made sense to me)... I pulled out the FSM. Seems as though #1 is ~5 o'clock. I set #1 TDC to 5 and wouldn't ya know. The motor cranked over three times and came to life.

Thanks for giving me the push to look at the FSM instead of my other source. Motor is broken in and ready to go.

Happens to the best of us. Gotta love the FSM. Mandatory for every vehicle I own and wrench on.

Glad you got it resolved......

Told ya!!!!!!!!! BTW, glad you got it running.

cruiser54 said:

Told ya!!!!!!!!! BTW, glad you got it running.

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Play nice now!

joe_peters said:

Play nice now!

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I can say that only because I've done the same thing in the past, sworn the distributor was correctly installed and looked elsewhere for the problem. LOL

What crappo manual shows #1 at 7 o'clock?

I could see a manual showing #1 being at 7 o'clock when standing @ front instead of 4 o'clock standing @ passenger side.

gradon said:

I could see a manual showing #1 being at 7 o'clock when standing @ front instead of 4 o'clock standing @ passenger side.

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Good point.