TJ won't fire up after frame swap

TJ4Jim

TJ4Jim

TJ Expert
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Joined
Dec 9, 2015
Messages
3,893
Location
Brookings, Oregon
Chili Pepper is back together and refuses to fire up, so it's time to put it out there. During the process the engine remained assembled except for a cleaning and restoration of accessories. At this point the pump primes properly and fuel pressure is good (intake manifold is wet) and she cranks with authority. When I set her on TDC and insert the distributor there is no attempt to fire with or without starting fluid but when I re-install the distributor 180 deg out she does attempt to fire. I set TDC with a vacuum/pressure gage on cylinder # 1 and when I pass TDC it goes into vacuum on the intake stroke with a half rotation then pressures up on the compression stroke. Distributor seats properly with the alignment lock down tab properly positioned over the bolt hole. I locked the rotor in the proper position with the alignment hole during the installation and the rotor is close to the #1 post on the cap.

Just pulled plug #2 and it is showing what I would consider a healthy spark.

She was running fine prior to the frame swap, I replaced the plug wires and coil with a new NTK coil as the original had internal rust expansion and numerous cracks. I have swapped all the old stuff back in with similar results.

My thinking keeps coming back to timing but at this point I'm hitting a mental wall, what am I missing here.
 
Did the oil pump get replaced?
The the crank get spun at all with the distributor out?

Hello from Brookings OR also. Small world, this internet thing.
 
707kevin said:
Did the oil pump get replaced?
The the crank get spun at all with the distributor out?

Hello from Brookings OR also. Small world, this internet thing.
Click to expand...

Did not touch any internals and no the engine was not spun originally, took a pic of the rotor prior to removal of the distributor and reinstalled in the same position. Since then I have reinstalled it based on my TDC location.
 
I have removed and reinstalled the distributor closely following the FSM with the crank at TDC, the locking tab at 1 o'clock, the oil pump drive at 10 o'clock and it rotates properly into position with the locking tab directly over the hold down bolt hole. The only thing I notice is the rotor is supposed to be at 3 o'clock (per fsm) when set and it is closer to 4 o'clock and a touch clockwise past the #1 post on the cap.
 
With the engine at TDC on #1 compression stroke, the rotor needs to be pointing at the #1 spark plug wire location on the distributor
 
Just took the distributor in and out 10 X in the last 20 minutes and had my son visually confirm all aspects of the process and we are both seeing the same thing.

When dropping the distributor in and all the gods are aligned the lockdown fork is about 3/8" past the bolt hole and does not align as the FSM states. It's close but not dead on.
 
Chris said:
So what does that mean?
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Well when the distributor rotates down into the gear it is supposed to align itself over the lock down bolt right on the money, but in reality it is missing the bolt hole by 3/8" when I rotate it in. Distributor shaft is locked in place thru the alignment holes per the FSM during the process.

Dist.JPG
 
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I just tried dropping the distributor in with the timing marks at about 8 deg before TDC and the dam hole lined up and she is trying hard to fire up.

I'm looking at removing the dam timing cover to confirm the timing marks but this is the last thing I want to do now.
 
I vaguely remember mine doing the same but this was probably 6 years ago. You're getting closer it sounds like!
 
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Well the old adage never disappoints, "Never Assume" and my fault was assuming TDC was actually correct.

Had a brain fart last night when trying to get some sleep and this morning I took my borescope and dropped it thru #1 plug to confirm TDC visually and guess what, the harmonic balancer is about two inches past the actual TDC and I have no clue how that is possible. I reset the distributor to the piston being at the top of the stroke and she fired right up and right now purring like a kitten.

I guess the balancer will have to be removed to discover why it is not keyed properly but at least it is not an invasive process.
 
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Outer ring on the damper spun on the inner hub. This happens sometimes on older engines. A new damper is the only solution . Inline 6 engines are neutral balanced, so a spun damper doesn't usually make the engine vibrate more.

If the outer ring spins on an engine with a weighted outer ring, look out. They can shake themselves apart in a hurry.
 
TJ4Jim said:
Well the old adage never disappoints, "Never Assume" and my fault was assuming TDC was actually correct.

Had a brain fart last night when trying to get some sleep and this morning I took my borescope and dropped it thru #1 plug to confirm TDC visually and guess what, the harmonic balancer is about two inches past the actual TDC and I have no clue how that is possible. I reset the distributor to the piston being at the top of the stroke and she fired right up and right now purring like a kitten.

I guess the balancer will have to be removed to discover why it is not keyed properly but at least it is not an invasive process.
Click to expand...

Excellent! The bonded rubber can eventually start to separate, and the inner hub and outer pulley surface come out of alignment. Replacements aren't too much $$ and it's a pretty easy job on a 2.5l A little less room to work on a 4.0 though.
 
Thanks guys, that is a very possible scenario so as soon as I am done dancing around my shop I'm gonna order a new one.
 
Glad you got it fixed!

So this is another case of Occam's Razor I take it?
 
Chris said:
Glad you got it fixed!

So this is another case of Occam's Razor I take it?
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Pretty much, My brain kept going back to the fact I was relying on the pulley mark so at first I used a big zip tie in the cylinder to see where the piston was and it was not making sense to me so out came the borescope and bingo.

Ordered a new harmonic balancer pulley but it will be a few days. Not easy getting off the radar parts around here, great parts stores but the do not carry a lot of Jeep stuff.
 
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