Igntion Coil...?

M

marbledmurrelet

Active Member
Had a bit of an adventure on Boxing Day...

Went out to pull our crab traps, after starting without issue, and warming the engine ('94 7.4L Mercruiser) up thoroughly, we left the dock about 5 minutes in cruising at 3400-3600 RPM (25mph) the engine cut out.

The engine made no noise or indication something was wrong, it was as if someone turn the key to off. Couldn't start the engine again, came in on the kicker...

The main engine is by no means an angel, it has had issues $$$$ in the past.

I am just looking for any incite as to what happened before we call in a "medic". I feel it is either the spark or fuel, I prefer the spark theory as the engine did not cough or sputter as it would if the fuel pump packed it in... it just cut off cleanly . The engine is trying to start but will not catch...

Any theory or ideas are welcome ( I have an opinion of the engine...lol)

Thanks,

MM
 
Might want to check distributor to see if your getting spark out of it. as I had similar problem just die for no reason then next day would start. came down to the electronic module was at fault. and yes was chasing a zombie JUST to find out it was the distributor.

hope that helps Wolf
 
Hopefully it is a simple matter and not catastrophic.

Do you have fuel for sure? Is it making it's way to the engine?

Do you have a kill switch/clip? Any chance it fell off by accident?

Have you done anything recently that could be impacting things?
 
Battery,alternator or neg. Post issues?
Is there voltage in the battery is there voltage going to starter when turned to start?
 
I think you will find it's an electrical issue because fuel or carb usually the engine from 3400 rpm will cough, sputter etc and try to keep running. Dead cutout-spark has stopped-engine stops immediately-fuel or no fuel. Any of the above electrical suggestions could/should be your answer. Good Luck!!
 
If the engine is turning over, then it's unlikely to be a battery issue. I'd be looking at the distributor/coil. Pull a plug wire, connect any old plug to it, ground the electrode, crank the engine and see if you get spark. An engine needs spark and fuel to run. If it's not one, it's likely the other.
 
This exact thing happened to me on my old 5.0ltr merc (chev)

I did " check spark at plug " and had some..but it was not enough to fire..so take warning that even though you might have some its not enough..

It was the coil in my case
 
Last edited:
have you been able to restart it yet?
my blind guess would be an ignition module in the distributor, or a short/open to the coil or distributor etc

id agree that its an electrical issue not fuel
 
try spraying some wd40 on the coil and leads. it displaces water. If water shorting the coil is causing the no start condition, this will often solve it. Had this happen periodically on an old boat I used to own... water would drip down the hatch when washing blood and guts off the deck. some of the water would end up dripping on the coil and hence, no start.
 
I will be back at the boat this weekend will try out some ideas and let you know.

Thank you all for your input, its nice to be able ask such an experienced group!
 
I personally dont use wd-40 on a boat corrosion block or something close to that wd is basically a glorified mineral spirit spray (paint thinner) and does not contain fish oil. its great for washing parts off though... and yes i love the **** too
way better things to use on your boat...
 
Pull a spark plug and put a screw driver in the boot (plug wire ) hold the metal 1/4 from the block and have someone crank it over a few times, should be a spark, if so, try and get a teaspoon of gas down the carb and turn over again should fire for a few seconds ( no fuel delivery), fuel pump, filters etc, if not pull the cap and turn over to see if rotor is going around and around, if not, mark and pull dist, if yes check all wiring first, is it fused. Let us know
 
i used to get moisture or condensation build up in the dizzy causing this... but it would fart and sputter.
 
Same thing happens with me when I get moisture build up. Only its usually rum and coke that causes me to get dizzy, fart and sputter. :)

Sorry for the sidetrack, but I couldn't resist.
 
It took me longer to get down to the boat...Feeling sheepish, if you look the problem was right in front of me the whole time...

The main cable from coil to distributor cap had come undone? didn't expect it to come off while running... scary.

I was about to start digging when the first thing I touch wasn't plugged in, silly.

Added some dielectric grease to the silver screws in the above photos as it seemed to be arching a bit, and the plugged boot it back in, "bang" stronger than ever.

MM
 
Is the end of the distributor wire damaged at all? I had a spark plug wire do that when I got my boat, the part that snaps/clips onto the end of the spark plug was damaged and missing a spring
 
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