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Merc 3.0LX No Spark

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MrHProblems

Contributing Member
This is going to be a relatively long one I believe.

Information:
1996 Bayliner Capri w/ 3.0LX Merc.

I stored the boat for the winter and came back this season to take it out on the lake and BAM, crank no start.

I narrowed it down to no spark, replaced the distributor, rotor, cap, etc(made sure to set the timing, it’s 8° before)
replaced the ignition coil,
bypassed the kill switch temporarily,
unplugged the shift disrupter( connected the 2 wires on the harness to each other),
Check continuity of all the plug wires,
Made my own EST-Coil wire harness because the factory one appeared to be bad,
New spark plugs,
Tach is unplugged from behind the gauge cluster,
All fuses are good.

I also tested to see if I’d get spark directly from the coil, no spark. I have 12 volts entering the coil via the purple wire that is in the same connector as the grey wire, I also have 12 volts leaving the coil through the harness to the distributor, as well as through the plug wires going from the coil to the distributor. Everything also appears to be grounded properly to my knowledge.

At this point I have no clue what else it could be.
 
Assuming all of the replacement parts are good, I would recheck the wiring on your harness. If that checks good, I would redo your voltage tests using a bulb type of test light (no LED testers as they dont draw enough current). make them with the KEY ON and engine off as well as during cranking...

If those checks are good, then I'd say you have to go thru and do the component tests on the 'new' parts to find the faulty one...with no spark directly out of the coil, that would leave the coil, the interconnects, and the internals to the distributor.

I know its 20-20 hindsight but changing one part at a time when you don't know what is bad usually reduces the total effort to get things going.

Finally, the factory service manual I have calls for initial timing at 1 deg BTDC...I have found over the years that its much easier setting an EST distributor's timing at max advance and ignoring the timing shunt exercise...
 
makomark said:
Assuming all of the replacement parts are good, I would recheck the wiring on your harness. If that checks good, I would redo your voltage tests using a bulb type of test light (no LED testers as they dont draw enough current). make them with the KEY ON and engine off as well as during cranking...

If those checks are good, then I'd say you have to go thru and do the component tests on the 'new' parts to find the faulty one...with no spark directly out of the coil, that would leave the coil, the interconnects, and the internals to the distributor.

I know its 20-20 hindsight but changing one part at a time when you don't know what is bad usually reduces the total effort to get things going.

Finally, the factory service manual I have calls for initial timing at 1 deg BTDC...I have found over the years that its much easier setting an EST distributor's timing at max advance and ignoring the timing shunt exercise...
Click to expand...
I did replace things one by one

But neither the old coil or this coil is creating a spark, I have plug wires showing up Thursday so hopefully that fixes it but at this point I'm at a loss for words on how something could go this bad over the winter stored inside a temperature controlled area.

Also no idea what you mean in your last message to ignore the timing shunt exercise, I'm new to boats but have lots of car mechanical background.
 
MrHProblems said:
I did replace things one by one

But neither the old coil or this coil is creating a spark, I have plug wires showing up Thursday so hopefully that fixes it but at this point I'm at a loss for words on how something could go this bad over the winter stored inside a temperature controlled area.

Also no idea what you mean in your last message to ignore the timing shunt exercise, I'm new to boats but have lots of car mechanical background.
Click to expand...
He means don’t bother setting base timing. Just use an advance timing light and set distributor to where you get the correct total advance specd for your engine . I think it is somewhere around 28-30 degrees total advance at like 3 k rpm .

This way avoids all the screwing around putting it in base mode, which sometimes doesn’t work
 
Dieter said:
He means don’t bother setting base timing. Just use an advance timing light and set distributor to where you get the correct total advance specd for your engine . I think it is somewhere around 28-30 degrees total advance at like 3 k rpm .

This way avoids all the screwing around putting it in base mode, which sometimes doesn’t work
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Oh gotcha, well regardless of that.

None of it matters if I can’t get spark, boat is still a massive paper weight. I can’t figure this out for the life of me.
 
MrHProblems said:
Oh gotcha, well regardless of that.

None of it matters if I can’t get spark, boat is still a massive paper weight. I can’t figure this out for the life of me.
Click to expand...
trace down what's listed for the voltage loss in the iboats thread... same guys here as there.
 
Have you replaced the ignition control module?

If I remember correctly, the spark can only be seen with a small gap. Like the spark plug itself. I worked on a few of these in the early/mid 90's and a regular spark tester (1/2 inch gap) wouldnt work. One of those jobs the control module was bad.

You say the wiring was a mess. That may have caused such a failure???
 
kghost said:
Have you replaced the ignition control module?

If I remember correctly, the spark can only be seen with a small gap. Like the spark plug itself. I worked on a few of these in the early/mid 90's and a regular spark tester (1/2 inch gap) wouldnt work. One of those jobs the control module was bad.

You say the wiring was a mess. That may have caused such a failure???
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I have not replaced the ignition control module, not sure where that is even at on the boat, but wouldn’t the boat not crank at all if that went.

^ ignore all of this ^

The EST is what your referring to and yes I have replaced that, kinda feels like the new one is also bad, might try putting the old EST back in with the new rotor/cap/etc and see if that works though.
 
makomark said:
pull the wires from the shift interrupter switch and connect them to each other
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Read in a few forums that if the shift interrupter was bad it would stop the spark because it would be stuck thinking it was in gear essentially, but regardless with them connect to each other, connected to the shift interrupter properly or disconnected entirely, nothing changed.
 
pretty sure that will put +12VDC onto the module pin as soon as the key is turned on...the Delco documentation states doing so may damage the module inside the distributor...
 
Here's one way to test the system out of a few.

You'll have to scroll through about 6 pages and maybe open a few of his suggest links to buy test equipment to see what they are, etc. but here is a step-by-step guide of how to test it, https://easyautodiagnostics.com/gm/4300-5000-5700/distributor-mounted-icm-tests

And probably still can buy them but there were a few testers one could buy to test them in the early days of the EST debuts...Even some auto stores offered a way to test them using test equipment...I don't think they still do though.

 
I keep a known good one in my tool box for debugging purposes...used to have an auto electric shop that could test many different kinds but he sold out years ago...

Probably fastest to get one from a local auto parts store....that said, the clones don't always behave like the OEM modules when running without an ECU controlling the timing...the Delco D1943A is known to behave well but you'll pay $75 or so for one...

You may want to try the one from the old distributor...worst case would be still no spark...
 
makomark said:
I keep a known good one in my tool box for debugging purposes...used to have an auto electric shop that could test many different kinds but he sold out years ago...

Probably fastest to get one from a local auto parts store....that said, the clones don't always behave like the OEM modules when running without an ECU controlling the timing...the Delco D1943A is known to behave well but you'll pay $75 or so for one...

You may want to try the one from the old distributor...worst case would be still no spark...
Click to expand...
Will update tomorrow with my results, please keep your eyes out!
 
Ironically, you can buy a new aftermarket distributor, complete, for less than $90...

I'd suggest just leaving the 4 pin connector free until you get spark to the plugs...
 
There is a piece missing here if you have been following the OPs thread on Iboats forum . Maybe he can share the link. He said he gets 12 v to coil with key on, but when cranking the 12 v cycles between 5 and 10 volts . I would think that is his issue that wiring corroded over winter causing a voltage drop. Would suspect with 5 v nothing will fire.

Have seen this on my brothers boat, took it out of storage motor wouldn't turn let alone fire. Wiring from helm to outboard was corroded such that there was like 6-7 ohms resistance from helm to plug at motor. It ran fine in the fall

edit - here is the link https://forums.iboats.com/threads/n...e-tried-everything.778861/page-2#post-5977757
 
Dieter said:
There is a piece missing here if you have been following the OPs thread on Iboats forum . Maybe he can share the link. He said he gets 12 v to coil with key on, but when cranking the 12 v cycles between 5 and 10 volts . I would think that is his issue that wiring corroded over winter causing a voltage drop. Would suspect with 5 v nothing will fire.

Have seen this on my brothers boat, took it out of storage motor wouldn't turn let alone fire. Wiring from helm to outboard was corroded such that there was like 6-7 ohms resistance from helm to plug at motor. It ran fine in the fall

edit - here is the link https://forums.iboats.com/threads/no-spark-feels-like-i’ve-tried-everything.778861/page-2#post-5977757
Click to expand...
So I should test the ignition wire from the helm all the way to the plug and see if it’s got a ton of resistance?
 
MrHProblems said:
So I should test the ignition wire from the helm all the way to the plug and see if it’s got a ton of resistance?
Click to expand...
That would be part of the diagnosis but wanted to bring up that if you only are getting 5-10 volts during cranking that’s your problem, it’s not enough for the system to run on.

I saw you updated the iboats post saying you jumped to the coil from the battery and still not spark. What was voltage while cranking. I would think if you you still don’t have a minimum of 10-11 volts cranking, you have a battery issue or the starter is drawing so much current that it drains the voltage while cranking

You can also do a simple bench test of either this or the old igntion system- hold dist in a vise, hook up power from known battery, turn dist with a drill should get coil to fire
 
Nothing like a missing details....

if the primary feeed is a concern, just bypass the ignition switch, harness and the multi-pin connectors with a fused jumper....

If you keep the 4-pin plug disconnected from the module, you minimize it and any recommended connections from having any adverse impact on the coil making a spark...
 
Dieter said:
That would be part of the diagnosis but wanted to bring up that if you only are getting 5-10 volts during cranking that’s your problem, it’s not enough for the system to run on.

I saw you updated the iboats post saying you jumped to the coil from the battery and still not spark. What was voltage while cranking. I would think if you you still don’t have a minimum of 10-11 volts cranking, you have a battery issue or the starter is drawing so much current that it drains the voltage while cranking

You can also do a simple bench test of either this or the old igntion system- hold dist in a vise, hook up power from known battery, turn dist with a drill should get coil to fire
Click to expand...
Will test voltage while cranking tomorrow along with the multiple other things I will be testing, also sucks because sourcing a starter and starter solenoid for this motor locally is hard.

Also will get the battery tested at my local auto parts store tomorrow too.
 
makomark said:
Nothing like a missing details....

if the primary feeed is a concern, just bypass the ignition switch, harness and the multi-pin connectors with a fused jumper....

If you keep the 4-pin plug disconnected from the module, you minimize it and any recommended connections from having any adverse impact on the coil making a spark...
Click to expand...
The 4 pin connector on my distributor only has 3 pins being used(ran like this last season), 2 of them are for the timing stuff and 1 of them appears to be the ground end of the shift interrupter circuit. I could be wrong though.

If you can go more into detail on the fused jumper that would be awesome.

It is just mind blowing to me that over the winter something like this could happen, it started up first crank right before being stored for the winter.
 
MrHProblems said:
The 4 pin connector on my distributor only has 3 pins being used(ran like this last season), 2 of them are for the timing stuff and 1 of them appears to be the ground end of the shift interrupter circuit. I could be wrong though.

If you can go more into detail on the fused jumper that would be awesome.

It is just mind blowing to me that over the winter something like this could happen, it started up first crank right before being stored for the winter.
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I’m facing the same issue with our sea doo

Starter won’t turn over started ok in the fall

My brother’s center console the conduit with the wiring and fuel lines from outboard up to hElm was full of water sat over the winter(s) and there was an enough corrosion finally built up no power was getting back to the outboard
 
From the main battery cable to the Purple wire just before entering the coil I have a 29.4 Kiloohm resistance reading...

Also I have a steady 10v reading while cranking on that purple wire when everything is hooked up normally.
When directly jumped to the battery I only get an 11v reading while cranking from the purple wire.
 
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After messing around with the wiring and undoing some electrical tape and such I know have a reading a 1.3 ohms from main cable to primary side of coil which is still a little high I believe.
 
MrHProblems said:
After messing around with the wiring and undoing some electrical tape and such I know have a reading a 1.3 ohms from main cable to primary side of coil which is still a little high I believe.
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assuming that is with the ignition key turned to RUN??

11VDC is enough for the ignition to work...I'd say its time for another ignition module.
 
makomark said:
assuming that is with the ignition key turned to RUN??

11VDC is enough for the ignition to work...I'd say its time for another ignition module.
Click to expand...
with the key off and the battery disconnected, cant test the resistance with a positive current from what I learned.

I was also reading that 11VDC is not enough to get the coil to fire?
 
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