Stumped on No Start Condition for Weeks Now

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T56MaxTorq

T56MaxTorq

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Was pulling very hard up a hill. Came over the other side and stalled at the stoplight 1/4 mile down. Found I Melted the center post on the distributor. Engine is in sig. 5.2 turbo, Megasquirt efi, e85. Changed all plug wires and the coil and the cap and rotor

So I’ve never gotten it to start and idle since. Just backfired once or twice and attempts to keep running. Strained the starter nicely. Cranks over at a little under 200 rpm. Valve timing was checked and it’s good. Threw the timing light on and it’s accurate. Cranks at 15 degrees btc. Even preheat the engine with a block heater. It’s getting fuel I can smell it. I honestly think it may be flooded with fuel still. Fat 44lb injectors and e85. But it then sat for a month and no change in the starting attempt condition. Haven’t attempted starting fluid with the backfiring going on. Plugs look ok. Can’t visibly tell if there’s any holes in piston tops or not. The megasquirt wiring looks good and it is reading and seems to operate accurately as far as I can tell. No faults. I can borrow a boroscope too. Other idea is a big vacuum leak but I blew off a 7/16 vac plug on the throttle body the same night and repaired it but I knew it because my idle was 2000 rpm.

Anything I’m missing? Oh and it’s getting spark while cranking and ign hot
 
Compression, Ignition, Fuel

Take a Spritzer bottle with Non-Ethanol gasoline and spray in the air intake with the butter fly open while someone is cranking It over.

☆☆☆☆☆
 
George Jets said:
Compression, Ignition, Fuel

Take a Spritzer bottle with Non-Ethanol gasoline and spray in the air intake with the butter fly open while someone is cranking It over.

☆☆☆☆☆
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That’s my last resort. Should start on its own tho. Even after sitting. I’ve thought to change the oil as well. May have a ton of alcohol in there I can’t tell. It hasn’t been mixed up from cranking but stick looks normal.
 
Borrow that bore scope or a compression tester. If you were pulling hard under boost and the ignition screwed up you may have detonated your pistons, or rings, or torched some valves. Backfiring would indicate you are getting a spark when you don't want it, really slow combustion or the cylinder isn't sealed.
 
Did you remove the distributor?
Also see if you can set it to TDC and see where the rotor is pointing, and verify a your plug wire that is going to cylinder #1
 
Can we maybe know all the details of the ignition? Like WHAT is it exactly?
 
Burnt dist cap = replaced dist cap = plug wires mis wired.

Describes back fire, no start symptoms
 
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JedIEG said:
Borrow that bore scope or a compression tester. If you were pulling hard under boost and the ignition screwed up you may have detonated your pistons, or rings, or torched some valves. Backfiring would indicate you are getting a spark when you don't want it, really slow combustion or the cylinder isn't sealed.
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Don’t doubt the worst but it didn’t make any scary noises and e85 is helpful. Bottom end is oem. No strange noises at the crankcase or oil separator.

Heywodja said:
Did you remove the distributor?
Also see if you can set it to TDC and see where the rotor is pointing, and verify a your plug wire that is going to cylinder #1
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No i left it alone and changed the cap and rotor. The oil pump drive gear is pinned so no worry about it ever slipping. I set #1 to tdc compression stroke and rotor is correctly positioned. Plug wires triple checked

RustyRatRod said:
Can we maybe know all the details of the ignition? Like WHAT is it exactly?
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It’s pretty wild. I use a crank trigger. 36-1 missing tooth wheel and a Hall effect pickup . That gives time for ignition and fuel. uses a Bosch bip373 coil driver. Uses a single coil, ford e style. Distributor distributes spark only. It runs off a timing map I designed. Today I set the timing to a fixed angle of 20 btdc instead of running the map. Haven’t tried to start it yet. Weather sucks.
 
Have to assume you pulled the plugs and looked at them. No burned ground straps etc? High resistance down stream probably burned the cap.
 
furrystump said:
Have to assume you pulled the plugs and looked at them. No burned ground straps etc? High resistance down stream probably burned the cap.
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I pulled 5 plugs that are easy to get to. 3 require loosening exhaust. They looked ok. E85 keeps everything too clean it’s hard to see much. Gaps are good. I think the center post boot may have slipped off while under that hard pull. Going to shove a scope in it this weekend. You’d think putting new wires and replacing a smoked cap on it would make some difference but it didn’t. I tried a lot to start it on the road because I had a jump. I still feel it’s flooded but no way I mean I have ring gaps of like .045” and a 100,000 mile standard size bore.

image.jpg
 
Just a thought, that e85 will draw a lot of moisture out of the air on humid days.

In Florida on a humid day you can pour 87 Octane 10% Ethanol into a soup can, within an hour it turns milky white as it draws the humidity out of the air.

That's why the Non-Ethanol goes into the small engines so they start easy.

☆☆☆☆☆
 
T56MaxTorq said:
I pulled 5 plugs that are easy to get to. 3 require loosening exhaust. They looked ok. E85 keeps everything too clean it’s hard to see much. Gaps are good. I think the center post boot may have slipped off while under that hard pull. Going to shove a scope in it this weekend. You’d think putting new wires and replacing a smoked cap on it would make some difference but it didn’t. I tried a lot to start it on the road because I had a jump. I still feel it’s flooded but no way I mean I have ring gaps of like .045” and a 100,000 mile standard size bore.

View attachment 1716184605
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If you think it has fuel still in the cylinders I’d remove all the plugs you can get to and crank it over with them out. Any left over fuel will blow out and you should be able to get it to fire with 5 clean cylinders.

Id also replace the plugs you can get to. That cap was failing long before it failed and it may have one or more of the plugs to fail. Weird things happen to other parts when stuff like that fails.

Of course I could be totally wrong and probably am. It was the best I could think of lol
 
As someone said, compression, spark, fuel

I would:

1....Run compression test and leakdown test.

2....Waste no more time with fuel. Squirt some fuel in the intake, just like you would if a carb was not getting fuel. Inspect plugs for wet/ foul

3....Devise a way to check cam timing. Since you are using a crank trigger, the fact that it seems to be in time now has nothing to do with where the cam might be

4...If no joy, I'd "rig" my infamous emergency ignition, and temp wire that up just like it had a carb. Crank it and see if it will fire on fuel down the intake

I think TrailBeast drew this nice diagram after my hen scratches

4pin-jpg-jpg.jpg


I threw this together to carry in the trunk and have never used it as such. I HAVE used it to test fire several old engines!!

hwlcfa-jpg-jpg.jpg
 
Did the plugs look glazed at all? I can't tell you how many vehicles I used to get towed in for a "no start" where a set of fresh plugs has it fire right up...I've never seen a magnum engine where exhaust had to be moved/removed to get to any spark plugs.
 
No compression on 4 cylinders. Valves touched pistons on 6 cylinders. 2 survived. Must have floated the valves.

IMG_2569.jpeg
 
Not sure how because I have a pathetic 8.5:1 compression. A .039 gasket, pistons were down the cylinder .047” and my cam isn’t even that large. Barely .5” lift
 
That's an interesting development. Can you check timing chain slop?
 
"barely .5"lift" seems pretty huge, no, humongous especially considering what these engines originally came out with I've seen timing chains jump on stone stock engines where the valves kissed the pistons
I had it happen to a Durango, 360 mag, brand new EQ heads that were supposed to be ready to run out of the box, but they had the guide clearance too tight, a couple of valves stuck on break in
(Stone stock bottom end, original cam it left the factory with still in place) and it bent a couple of valves on me
 
mopar head said:
Chain
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Maybe but I have doubts. It was a strong double roller and I had a v6 tensioner. I’ll check for slop.

volaredon said:
"barely .5"lift" seems pretty huge, no, humongous especially considering what these engines originally came out with I've seen timing chains jump on stone stock engines where the valves kissed the pistons
I had it happen to a Durango, 360 mag, brand new EQ heads that were supposed to be ready to run out of the box, but they had the guide clearance too tight, a couple of valves stuck on break in
(Stone stock bottom end, original cam it left the factory with still in place) and it bent a couple of valves on me
Click to expand...

Cam is .490” 218/218 115 Lsa. Fairly mild cam. I think I floated the valves. These are EQ heads. Have about 2000 miles on this engine. Zero issues.
 
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