1988 88 SPL Johnson Intermittent spark

[smak90]

I'm helping a buddy who bought old 1988 McKee Craft boat and motor that had been sitting at least a couple years. I drained the fuel tank which had a gallon of water and really bad fuel separation going on, rebuilt the carbs, set the timing (which had issue I'll talk about in a minute). I replaced all fuel lines in boat and engine. I've got it idling really good. We took it out yesterday, it started up and idled good. We gave her full throttle and she immediately got up and hit 5000 RPM for about 5 seconds, then it dropped to 4000 RPM for 5 seconds and then dropped to 3000 and that was all she had after that. I pumped the fuel bulb and it had no affect. We let the boat sit an hour and repeated the above trial and and had the same results, boat immediately gets up to speed and quickly loses RPMs over the next 5 to 10 seconds. I'm ruling out fuel issue since we get the RPMs immediately when engine is really cold and pumping the bulb has no impact on the performance.

I checked spark with a 7/16 gap and I didn't get spark from bottom 2 cylinders (top 2 had great spark). When we got back to the house and we tested spark again we weren't getting spark to jump a 7/16 gap on the top 2 cylinders but we were now getting it on the bottom 2. So basically the cylinders with bad spark seem to be moving around. I didn't have my DVA multi meter with me so I didn't go into any further testing.

When setting timing earlier (using Joe Reeves method from top-secret files), the timer base would not rotate to the full forward position. I could push it from all the way back (0 degrees) to 3/4 of the way forward to give me an advance of 24 degrees (reading 20 degrees on the timing light using Joe Reeves method). I'm assuming at this point the timing base needs to be replaced unless I can find some obstruction when I pull the flywheel.

When I inspected the power pack it appears to be brand new. My theory is previous owner replaced it when it quit running right, it didn't fix the problem and the boat sat for years after that.

My question is do the symptoms in combination with the timer base not advancing indicate timer base is likely the problem or it there a good chance I'm seeing 2 separate issues and the intermittent spark problem is really the stator or power pack (even though it appears new)? I have limited time to help my buddy who lives an hour away and I'm wondering if I should go ahead and order a timer base before troubleshooting further with the DVA multimeter?

Thanks in advance for your help.

 

[Bosunsmate]

Its not overheating is it? An an overheat horn not working? Some of them go into slow mode and drop down the rpms, ive forgotten if that means they cut spark to half the engine or not.
Also did you try manually moving the timing base, or just by the throttle controls?
Sometimes dried up grease will stop them advancing, i dont grease mine at all, to fix that you need to undo it and clean all the grease and grit out.
24degs cant be far off waht you are after and to have another 1/4 to go sounds like the timing must get really advanced if it is meant to go another quarter

 

[Bosunsmate]

Also id get your mate to get a $10 multimeter and do the ohmn testing on stator and timing base.
The timing base not advancing shouldnt cause the spark to not work on half the cylinders.
Both those things are expensive so are a real imposition if they are not whats needed.
Spark dancing around sounds more like powerpack to me, those things do all sorts of whacky stuff when they go but then again i wouldnt be blown away if it was the timing base failing, but it not advancing wouldnt cause spark to not go to two cylinders

 

[Bosunsmate]

I suppose what im saying is you or him really need to test those parts with at least an ohmn test to see what turns up before you decide as electrical components are only very rarely refunded after purchase and from what your saying means theres nothing which says pick me as the definite problem

 

[emdsapmgr]

As Bosun says, ignition parts are not cheap, so some time spend testing a couple of components is worth it. Ignition problems are likely, based on your comments. Weak ignition components tend to fail once the engine heats up to normal operating temps. Run fine when cold, crap out when warmed up. You want to validate both the timer base and the stator first. Start with the stator-if it's weak it won't put out enough voltage to fire each coil every rpm. You can best test it by comparing cranking voltages with the ones shown in the ignition troubleshooting guide found on this website: cdielectronics.com. You will need to use/borrow/rent a special "peak reading" voltmeter. When cranking you should see something like a minimum of 150 volts from the stator. Less than that and it's condemned. When you are in there, also check the cranking voltage output on the timer base. It should output something like 0.3 or 0.6 volts, depending on the chart on the website. Start there with your checking-see what you find.

 

[smak90]

It is definitely not overheating as we monitored it with an infrared thermometer while running. I also tested the overheat horn and it is sounding when I ground the sensor wires on each of the heads. His engine doesn't have the SLOW mode technology.

I kind of had a feeling the answer was going to be exactly what ya'll told me - test and troubleshoot each component. It looks like I'll be making at least a couple more trips out to his place to work on his engine. I've already got the multimeter with DVA that I used on my old 1994 88SPL which eventually was blown, and my 1980 85HP Johnson that replaced it so I'm pretty familiar with working on the crossflows. Thanks for confirming what I already suspected in the back of my head, I appreciate all the help and guidance you guys provide.

 

[racerone]

Check all the pins and sockets at the rubber plug in connecters.

 

[V153]

Assuming that's a CD4 ignition with single power pack? Regardless it's odd to have the spark(s) move around. That would lead me to believe it's a bad connection(s).

Timer bases in these things rarely go bad but it does happen. I recently lost spark in #2 and then #4 went dead just as I was checking?! Really weird.

Even weirder was the timer base resistance checks all tested good. But changing it out is what solved the problem?

 

[Bosunsmate]

Assuming that's a CD4 ignition with single power pack? Regardless it's odd to have the spark(s) move around. That would lead me to believe it's a bad connection(s).

Timer bases in these things rarely go bad but it does happen. I recently lost spark in #2 and then #4 went dead just as I was checking?! Really weird.

Even weirder was the timer base resistance checks all tested good. But changing it out is what solved the problem?

Maybe it was just bad connections...:laugh:

 

[V153]

Maybe it was just bad connections...:laugh:

Ha ha ha!!! Boy I don't think so. Hope not. You're not gonna make me go out & put the old one back on are you? Heh heh heh.

Here's a good one: Buddy has a '80 something 115. Had no spark in one cyl. Cain't member which now.

Anyway. To make a long story short. After swapping all kinds of chit & still scratching our heads. Turned out to be a plug wire ...

 

[smak90]

Thanks for the additional input, It looks like I may be in for a challenge for figuring out where the problem lies. I suspect the reason the previous owner let the boat sit and was selling it was because he couldn't figure out the problem, especially since the power pack looks brand new (which I won't let that fool me into assuming it's good). I'm guessing there is going to be some head scratching on this one since it starts and idles, gets up to high rpm fine before it starts losing spark and missing. Luckily, I love working on these type problems and figuring out the cause.

It may be a week or 2 before I get back out to work on it, since there's a lot of cold, wet and icy in the forecast this weekend. I'll keep you posted on what I find.