Thread: puzzled

Originally Posted by RM Fishin

mid 80's

I have had one of that era that had a bad powerpack and made it act like it was only running on 1 cylinder despite showing good spark on a spark test. But those ignition problems are typically either p[resent all the time or they show up after it warms up which is the opposite of what you have going on. Sounds to me like it is a fuel issue. I'd start at step 1 and work up from there just to rule everything out and get a good baseline. I'd check compression first and then see if you are getting spark that will jump a 3/8" gap. I'd then replace the fuel lines from the barb on the motor pan side to the fuel pump and pump to the carb with clear fuel line. I always add a clear inline fuel filter somewhere in that run as well. Then pull the carb and at least inspect it and blow out the low speed circuit and high speed jet with carb cleaner and compressed air. I also always replace that gray fuel line that comes on the premade primer bulb lines with regular black automotive fuel line that doesn't have a liner in it. Finally I would bench test the ignition components. CDI Electronics has the test procedures and specs on their site somewhere. I have a factory service manual too and if I can find it I will post it here.

If anyone needs a spark tester, This is what I use and is the best I have ever had. Shows clearly the rate and quality of fire to the plug very nice and bright. Easy to tell if you have a coil issue, wire issue, or intermittent fire.
Scout mentioned CDI - a while back I had to replace my stator on my Mercury 115, and went with the CDI stator - outstanding product, far superior to the Quicksilver replacement. Good folks and good products, for sure.
Amazon.com

Originally Posted by TheGrandPoohBah

If anyone needs a spark tester, This is what I use and is the best I have ever had. Shows clearly the rate and quality of fire to the plug very nice and bright. Easy to tell if you have a coil issue, wire issue, or intermittent fire.
Scout mentioned CDI - a while back I had to replace my stator on my Mercury 115, and went with the CDI stator - outstanding product, far superior to the Quicksilver replacement. Good folks and good products, for sure.
Amazon.com

Yeah those are handy, I have one as well. I typically first use the adjustable air gap testers that you run to ground to make sure the spark is super strong when you turn the motor over. Then I will use the tester you linked while running the motor to see if the spark drops off or stays consistent while running. Only complaint with mine is it's impossible to see unless in low light conditions.

I work on boat's for a living. We see the sea foam guy's (boat's) about one every 2 weeks. Keep in mind we're out 4 weeks at shop. About 45-50 , we've not looked at yet. Sea foam is ok for small 6 gal. tanks that get sloshed around, when using very little. In onboard tanks (21- an up gals.) Sea foam suspends , and doesn't mix well. And ends up being a problem.
4 mechanic's at shop. I've seen myself around 10-12
this year, where customers thought sea foam is the fix. And end up going thru carbs. and there full of red
crap. We highly recommend using only non- ethanol gas, if you use ethanol gas burn it quick. Google videos on YouTube , where they take both gas, in mason jars in front of a fan in high humidity conditions and watch the amount of water absorbed
with the ethanol gas . It's amazing. We have a 100 gal. tank on a jet ski trailer, with electric pump that we use just for this type situation.

As far as spark tester. CDI has what's called the neon in line tester, you hook to each spark plug wire
And run motor in test tank. Our tank handles 250 hp.
You can see if spark is breaking down. But the old school way of testing (stator,charge coil or trigger , pick up sensor) is the easiest using a dva.

Originally Posted by scout-j-m

Yeah those are handy, I have one as well. I typically first use the adjustable air gap testers that you run to ground to make sure the spark is super strong when you turn the motor over. Then I will use the tester you linked while running the motor to see if the spark drops off or stays consistent while running. Only complaint with mine is it's impossible to see unless in low light conditions.

That was my problem with my older testers, but this one is insanely bright in full sun. Lisle did a good job on this one, shows rate and quality quite well. It tipped me to a coil getting weak on a Kawasaki Twin on my riding mower that was still running pretty good, but it had one spark plug that never looked as good as the other. I cleaned and swapped the plugs around, and "Ah HA!". Wires ohm'd out, new coil did the trick! Mower now runs with more power, fer sure!

I need to get a good one of those myself. I have an old adjustable one that is not all that good