1988 3.0L Merc Loses Spark, Baffled!

[1MeanC3]

My name is Patrick, and I'm from Lake Placid, NY. My boat is a 1988 Glastron X-19. MCM 3.0L Merc I/O 130hp/181ci, the engine is original to the boat. My vessel is showing a no-spark issue after warm-up. It's in excellent shape for its age, and is well taken care of. We store it inside all winter, with a cover on it.

A little history... My parents purchased the boat brand new in 1988, and for the 21 years following, we enjoyed flawless operation of the boat. The last three years haven't been as good. After throwing $100's into parts, we're still breaking down afloat. Let me explain: On cold start, the boat fires right up and runs fantastic. Pulls strong and smooth down the lake for 20-25 minutes. You'll feel a quick hiccup, and then the boat dies right out in about a minutes time. It bogs down and backfires some, and then just plain quits. Upon placing a spark tester inline, there is absolutely zero spark after the engine dies. Waiting 30-45 minutes allows the engine to cool, the spark to return, and the boat to fire. It will start right back up and run great for another 15-20 minutes. Usually just long enough to get back to shore, or close.

The boat has brand new plugs, and brand new wires. We replaced the breaker points ignition last season (in hopes of resolving this issue) with a Pertronix Ignitor 2 electronic ignition kit, and there's a Flamethrower coil on it as well. The problem persists. We're getting into some great boat weather here in the Adirondacks, and I hate to lose another season of boating to an ill mannored boat that looks better than it runs.

I have taken a bunch of pictures, and retrieved all the numbers off of this thing that I could find, so that I have all the correct information the community here needs to (hopefully) help me get this thing running like it used to. If there are any other numbers I can find, or photos I can take, please let me know. I've talked to more 'marine' mechanics than I can count, and just as many shade tree 'boat guys' to no avail. I'm at my wits end here!

Drive serial: 0B891040, Transom serial: 0B942260.
MCM MerCruiser 3.0L I4. 181ci/130hp. Alpha 1 Stern Drive.
The casting numbers on the carb side of the block are as follows, from top to bottom: 12557, 42673, and a big 2.
Again, my boat: 1988 Glastron X-19













Any and all help is GREATLY appreciated, I just want to get back out on the lake and enjoy a couple Coronas!

 

[1MeanC3]

Re: 1988 3.0L Merc Loses Spark, Baffled!

The other six pictures I took:

 

[Don S]

Re: 1988 3.0L Merc Loses Spark, Baffled!

When you have a no spark condition, do you have power to the + terminal of the coil?
My guess you have found that just throwing parts at it is not the best way to cure a problem. Finding the problem takes troubleshooting so you replace the bad parts, not all the good ones around the bad one.

Here is where you find your engine serial number.
Can even see part of the number stamped in it.

 

[stonyloam]

Re: 1988 3.0L Merc Loses Spark, Baffled!

It looks like you still have the purple resistance wire on the coil. That will not do with the Petronix, you need a full 12V to the coil and Petronix module to make it work properly. Remove the purple wire (that goes from the carb. choke to the coil), and replace it with a stranded copper wire (solder splice it in near the choke connector). See if that helps.

 

[1MeanC3]

Re: 1988 3.0L Merc Loses Spark, Baffled!

When you have a no spark condition, do you have power to the + terminal of the coil?
My guess you have found that just throwing parts at it is not the best way to cure a problem. Finding the problem takes troubleshooting so you replace the bad parts, not all the good ones around the bad one.

Here is where you find your engine serial number.
Can even see part of the number stamped in it.

View attachment 199669

Whoa! I didn't even see that plate there!

I BELIEVE I had power at the coil, I checked a bunch of things w/ the test light and everything lit up, but I'm going to take another run Sunday if the rain holds off & double check.

It looks like you still have the purple resistance wire on the coil. That will not do with the Petronix, you need a full 12V to the coil and Petronix module to make it work properly. Remove the purple wire (that goes from the carb. choke to the coil), and replace it with a stranded copper wire (solder splice it in near the choke connector). See if that helps.

So you're talking the solid purple wire, not the purple/yellow, correct? I want to re-route the wire from BEFORE the carb to get a full 12v to the coil?

 

[stonyloam]

Re: 1988 3.0L Merc Loses Spark, Baffled!

So you're talking the solid purple wire, not the purple/yellow, correct? I want to re-route the wire from BEFORE the carb to get a full 12v to the coil?

Yes the solid purple. The p/y wire comes from the slave and provides 12V to the coil during starting. You want to REPLACE the purple wire with a stranded copper wire. Remove the purple wire from the coil, tape off the end and wrap it up out of the way. Splice the new wire into the purple wire going to the electric choke, and run it to the coil + terminal.

 

[jl_photo]

Re: 1988 3.0L Merc Loses Spark, Baffled!

I havent worked on a inboard/outboard in years, but I remember having a similar problem with the micro switches on the throttle linkage. There is at least 1 tiny switch that momentarily kills the spark just as you shift into gear. This momentary interruption slows the engine just enough for a smooth shift. It gets hot when the engine warms up and may be the source of your electrical problem.

Try making a pigtail with a small 12v light that will light up whenever there is power to the coil. and temporarily zip tie it near the dash. one wire to the coil + and one wire grounded to the block.

Another thing you might test is the ignition switch and related wiring. Wires heat up when in use, especially when there is a bad connection. Unlike A/C current, D/C requires very clean tight connections. Soldier connections whenever possible.

check the coil ground wire. The coil must have a good ground.

If you have any other electrical problems with the gages, running lights, accessories ect, it may point to an electrical problem with the fuse block or ignition switch.

 

[Chef Shawn]

Re: 1988 3.0L Merc Loses Spark, Baffled!

The purple from the choke is tied to the purplish/pink going to the coil. Just don't connect it. They are joined in the loom. The purple from the alternator feeds the choke.

 

[stonyloam]

Re: 1988 3.0L Merc Loses Spark, Baffled!

You want to leave the purple wire to the choke there, and splice the new wire into that wire.

 

[Chef Shawn]

Re: 1988 3.0L Merc Loses Spark, Baffled!

Correct, Stony, I MEANT don't to connect it to the coil.

 

[PeterB26]

Re: 1988 3.0L Merc Loses Spark, Baffled!

What is being referred to here is the Merc resistance wire to the coil. Merc thought it was a good idea to use a length of wire the changes resistance as it heats up. The thinking was at cold start the wire delivered fulll volts to the coil for a strong spark, but once warmed up the wire incresed in resistance and less voltage was delivered to the coil.

Now if you are running the old coil you can test this wire by jumpering it out with ordinary wire. I just use a length of wire with a coule of alligator clips, which is a darned handy thing to have in your tool kit anyway. If that fixes things then you know it is the resitance wire. But if you are still running the OEM coil you can't run it with regular wire for long. Put a proper resitance wire back in. Regular wire will toast your coil in time.

If you try to test this wire with just one of those simple tester lights you won't catch that it is delivering something less than the require voltage when its warm. There probably would be enough voltage to light the test lamp, but not enough to charge the coil.

If you have not recently upgraded your ignition system, it is much more likely a bad coil than a bad resistance wire. Old coils often fail in a way whereby they work OK until they heat up, and then they fail. (the coil heats up, not just the resistance wire.) They cool off and run fine again....

Precisely what you have described.

Peter

 

[sptjet90Reflexx]

Re: 1988 3.0L Merc Loses Spark, Baffled!

I also had no spark on my 4.3l 89 merc. turns out I just had a REALLY badly rusted ground and after I cut that and made a new ground at a different location it ran great.

 

[1MeanC3]

Re: 1988 3.0L Merc Loses Spark, Baffled!

Okay, I did make it out onto the lake today like I had planned. Removed the purple wire, and the problem still persists. Also, there is a wire run from the ignition switch right to the coil. Again we sat dead in the water for around a half hour before being able to get underway again. Did some playing with the throttle switch, but not sure we gained any ground... Starting to think it may be the Pertronix module/distributor. Once the boat finally started running again, it seemed like it kept dropping cylinders off and on, which also pushes me towards distributor. Someone above asked if I had power at the coil after the engine dies, and I do. The coil never loses 12v. That means the problem has to be between the coil and distributor, correct? At a loss here... This thing is fighting me!

 

[1MeanC3]

Re: 1988 3.0L Merc Loses Spark, Baffled!

What is being referred to here is the Merc resistance wire to the coil. Merc thought it was a good idea to use a length of wire the changes resistance as it heats up. The thinking was at cold start the wire delivered fulll volts to the coil for a strong spark, but once warmed up the wire incresed in resistance and less voltage was delivered to the coil.

Now if you are running the old coil you can test this wire by jumpering it out with ordinary wire. I just use a length of wire with a coule of alligator clips, which is a darned handy thing to have in your tool kit anyway. If that fixes things then you know it is the resitance wire. But if you are still running the OEM coil you can't run it with regular wire for long. Put a proper resitance wire back in. Regular wire will toast your coil in time.

If you try to test this wire with just one of those simple tester lights you won't catch that it is delivering something less than the require voltage when its warm. There probably would be enough voltage to light the test lamp, but not enough to charge the coil.

If you have not recently upgraded your ignition system, it is much more likely a bad coil than a bad resistance wire. Old coils often fail in a way whereby they work OK until they heat up, and then they fail. (the coil heats up, not just the resistance wire.) They cool off and run fine again....

Precisely what you have described.

Peter

I think that the Flamethrower was installed along w/ the Pertronix unit... I know originally it didn't have a Flamethrower in it. I'm thinking about pulling my buddies distributor out of his boat & giving it a shot in mine. How can I save the timing?

 

[Artwerke]

Re: 1988 3.0L Merc Loses Spark, Baffled!

If you pull the distributor you will have to reset the timing,no way around it.

 

[1MeanC3]

Re: 1988 3.0L Merc Loses Spark, Baffled!

I took a few pictures tonight before I covered the boat up...

Here is the current state of the coil, you can see the purple wire taped.


This is the engine plate, almost legible, i'll try for a better picture. The flash washed it out:


And I figured I'd give you guys a shot of my boat, since I haven't yet. Put a paint job to all of these engine pictures ;-).


Long story short, end result with the purple wire disconnected is the same as before, with it connected. How do I set the timing for this thing if I swap distributors? Is there a tutorial/how-to for that?

 

[Eric 3.7LX Alpha 1]

Re: 1988 3.0L Merc Loses Spark, Baffled!

Personally, I think pulling the distributor most likely won't change anything. Think about it. What is it doing? The only job is to turn that rotor, and the oil pump at the opposite end, now that the points are removed. It's super basic.

Maybe there's a wire with a bare spot and it will short to ground, the wire to the shift interruptor or the tach pick up lead on the (-) terminal of the coil? When it happens maybe try and disconnect those wires off the coil and see if any change?

 

[1MeanC3]

Re: 1988 3.0L Merc Loses Spark, Baffled!

Personally, I think pulling the distributor most likely won't change anything. Think about it. What is it doing? The only job is to turn that rotor, and the oil pump at the opposite end, now that the points are removed. It's super basic.

Maybe there's a wire with a bare spot and it will short to ground, the wire to the shift interruptor or the tach pick up lead on the (-) terminal of the coil? When it happens maybe try and disconnect those wires off the coil and see if any change?

We did take the wires off of the neutral switch and 'jump' it, but it didn't appear that anything changed. Still no spark. So you're suggesting removal of two wires on the coil while operating? Or as we lose spark? Its normally pretty abrupt. You hear a quick miss in the engine, all seems fine for a few seconds following, and then it starts to die out.

 

[Eric 3.7LX Alpha 1]

Re: 1988 3.0L Merc Loses Spark, Baffled!

That test is after you loose spark, but still have power on the (+) side of the coil.

Couple things that can kill spark is the shift interruptor and the tach.

Yeah, you don't want to jump those wires on the shift interruptor, that will ground the (-) terminal on the coil and kill the engine. Just like the shift interruptor will. They are normally (not connected) and when the shift interruptor engages it (connects the wires)

Just remove it and the tach off the coil to be safe.

 

[PeterB26]

Re: 1988 3.0L Merc Loses Spark, Baffled!

Okay, I did make it out onto the lake today like I had planned. Removed the purple wire, and the problem still persists. Also, there is a wire run from the ignition switch right to the coil. Again we sat dead in the water for around a half hour before being able to get underway again. Did some playing with the throttle switch, but not sure we gained any ground... Starting to think it may be the Pertronix module/distributor. Once the boat finally started running again, it seemed like it kept dropping cylinders off and on, which also pushes me towards distributor.

Its a bad coil.

You are so close, but why won't you try a new coil first? It is a bad coil! This is classic coil failure. They heat up and die. Cool off and run OK. Jumpering the resistance wire and getting the same result just means it isn't that wire, or the power to the coil... It is the coil itself.

Change the coil.

Peter