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Merc 3.0LX No Spark

It all depends on the ignition coil/wiring diagram.

Most electronic ignition coils are internally resistered. So full iign/battery voltage goes to the coil.

The old point ignitions used a ballast resistor and GM and Mercruiser used a~ 2 ohm resistor wire.

Question. Is it possible someone swapped the engine wire harness with and older one? A very older one and spliced the wires needed for your ignition system?

do you have a schematic for your engine?
That would help.

Is your coil the old standard "beer can" type
 
kghost said:
It all depends on the ignition coil/wiring diagram.

Most electronic ignition coils are internally resistered. So full iign/battery voltage goes to the coil.

The old point ignitions used a ballast resistor and GM and Mercruiser used a~ 2 ohm resistor wire.

Question. Is it possible someone swapped the engine wire harness with and older one? A very older one and spliced the wires needed for your ignition system?

do you have a schematic for your engine?
That would help.

Is your coil the old standard "beer can" type
Click to expand...
Harness looks factory

Coil is not the old beer can type, its like this one.

I do not have a schematic for my engine sadly.
 

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UPDATE:

Spark was achieved on the bench test with the old Ignition Module, new cap/rotor/etc and new coil/spark plug wire.

I have a tee time I have to get to but after I am done on the course I will be retiming the motor and reinstalling the distributor and coil and hoping for spark.
 
Wow, Thats fucked up...

When did they decide to put 12 volts through the shift interupt switch....

What is the reason for this?

I see a lot of issues causing problems when that wire hits a ground or some other issue done by someone who doesnt know....including me!!
 
Note: Based on schematic, it appears that full battery/ignition voltage is going to coil. No resistor wire/ballast shown.

Now thats not to say that the resistance from ign switch thru connector to coil wont have some resistance. But I think its safe to say when running above 1500 rpm there will be ~ 13 VDC at coil
 
kghost said:
Wow, Thats fucked up...

When did they decide to put 12 volts through the shift interupt switch....

What is the reason for this?

I see a lot of issues causing problems when that wire hits a ground or some other issue done by someone who doesnt know....including me!!
Click to expand...
The Delco EST needs 12 V positive in to provide the interrupt versus grounding the coil that kill spark in a point ignition
 
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Dieter said:
The Delco EST needs 12 V positive in to provide the interrupt versus grounding the coil that kill spark in a point ignition
Click to expand...
On the thunderbolt ign the white with green wire which goes to the sensor pickup and timing module gets shorted to ground. this ignition seems to get 12 volts to the sensor to interupt.... I wonder why?
 
They implement the shift interrupt function (at least) two different ways on the EST ignition...this is the stand alone mode. I'm pretty sure it just bumps the timing control to fixed mode, which slows the engine enought to allow the lower unit to disengage...

On the early MEFI alphas, they but the shift control switch inline with the IC signal between the module and the ECU...which provides the same end result...

I didn't check but remember the newer MEFI bravo engines go back to the original scheme where the shift interrrupt switch provides a ground when active...but instead of that killing the ignition trigger, it goes direct to the MEFI box and the ignition transient is implemented in the software...

When in doubt, check the factory data....not always perfect but usually the best source...until you come across a modified engine....
 
Your ignition timing is off… the initial timing shouldn’t be 8°…. Check the specification numbers on top of the flame rest cover., the timing number should be on there for best accuracy.
 
Fun Times said:
Your ignition timing is off… the initial timing shouldn’t be 8°…. Check the specification numbers on top of the flame rest cover., the timing number should be on there for best accuracy.
Click to expand...
Set the motor to 1 degree BTDC and installed the distributor, still experiencing the same issue, backfire through the carb.
 
MrHProblems said:
Set the motor to 1 degree BTDC and installed the distributor, still experiencing the same issue, backfire through the carb.
Click to expand...
Veryfify firing order, rotate the distributor while someone cranks it . Would think timing is off such that it doesn’t run
 
are you sure the timing was set with #1 on the compression stroke?

Sounds like the battery wasn't charged or the cablesconnections aren't in the best shape...
 
Firing order from the 4 o’clock post 1-3-4-2

Will be having a friend help me later tonight so hopefully we can either figure it out or follow up with more info for yall.
 
makomark said:
are you sure the timing was set with #1 on the compression stroke?

Sounds like the battery wasn't charged or the cablesconnections aren't in the best shape...
Click to expand...
I lined up the notch in the crankshaft pulley to the position 1° BTDC on the notched plate thing before setting the distributor.

Battery did seem to start getting low but that doesn’t explain the backfire through the carb though.
 
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Its sounds like you have the correct firing order. Are you 100% sure that you have the wires on the distibutor in the right locations.... excitement can cause over looking the basics.... just asking...
 
kghost said:
Its sounds like you have the correct firing order. Are you 100% sure that you have the wires on the distibutor in the right locations.... excitement can cause over looking the basics.... just asking...
Click to expand...
I will send a pic of the firing order I have in a few mins
 
MrHProblems said:
I lined up the notch in the crankshaft pulley to the position 1° BTDC on the notched plate thing before setting the distributor.
Click to expand...
if you did that (above) but didn't check to make sure #1 was on the compression stoke, then the distributor is 180 degrees out...the details matter...
 
MrHProblems said:
I lined up the notch in the crankshaft pulley to the position 1° BTDC on the notched plate thing before setting the distributor.

Battery did seem to start getting low but that doesn’t explain the backfire through the carb though.
Click to expand...
Yes but were you on 1deg BTDC compression or exhaust stroke?
 
makomark said:
if you did that (above) but didn't check to make sure #1 was on the compression stoke, then the distributor is 180 degrees out...the details matter...
Click to expand...
so you are saying I could've had a different cylinder on the compression stroke?

The only way I can turn the motor over is by the key, I cant get a wrench or socket anywhere on the crank shaft pulley to turn it over and the alternator doesn't turn the system either.

So I was just inching the motor around with the key to line it up.
 
makomark said:
if you did that (above) but didn't check to make sure #1 was on the compression stoke, then the distributor is 180 degrees out...the details matter...
Click to expand...
would it be fine to just rotate the distributor 180 degrees or should I with the help of my buddy just retime it entirely to the compression stroke?(if that is the problem)
 
yes but then the next time somebody goes to work on it, things won't be where they are expected to be...another hack (assuming the distributor was set 'close enough' would be to relocated the plug leads two posts....but that doesn't fix the not in standard location problem...
 
makomark said:
yes but then the next time somebody goes to work on it, things won't be where they are expected to be...another hack (assuming the distributor was set 'close enough' would be to relocated the plug leads two posts....but that doesn't fix the not in standard location problem...
Click to expand...
The distributor was set IMO perfectly on the exhaust stroke at 1° BTDC lol
 
MrHProblems said:
The distributor was set IMO perfectly on the exhaust stroke at 1° BTDC lol
Click to expand...
Impossible....

You set base static timing when the intake valve closes (base circle when both valves are closed) before exhaust opens...mechanically set marks to zero. Marker plate and harmonic mark. Then install distributor as close to #1 plug terminal lining up with rotor buy turning dist.

Then when trying to start, you may have to turn dist to get it to start. Then adjust for actual.

Rethink your approach...
 
kghost said:
Impossible....

You set base static timing when the intake valve closes (base circle when both valves are closed) before exhaust opens...mechanically set marks to zero. Marker plate and harmonic mark. Then install distributor as close to #1 plug terminal lining up with rotor buy turning dist.

Then when trying to start, you may have to turn dist to get it to start. Then adjust for actual.

Rethink your approach...
Click to expand...
Did you read the whole conversation?
 
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