Johnson 9.5 Weak Spark

[Bonger6]

Hey guys....first off I'm relatively handy and mechanical - but diagnosing electrical is not my strongest attribute.

I've got a mid 60's Johnson 9.5 that belonged to my wife's family that we had running well last year. This year it did for a couple runs but then I seemingly lost power. I determined I'd lost spark in the bottom cylinder and popping off the flywheel revealed why as one coil was literally missing chunks/falling to pieces.....no problem I figured, I'll just replace them.

Since the working coil didn't look a hell of a lot better, I ordered a couple aftermarket ones from Amazon that had relatively good reviews as replacements and put them on. Now...I get spark on both plugs but they are both SUPER weak. Not even strong enough to fire the engine. Before I removed the old coil (the working one) I had checked it and had very good/bright spark so now I'm wondering if both these coils are junk or if I've got something else going on or where I should start testing.

One thing that I will start with is pulling the coils and trim back - or replace completely - the spark plug wires to ensure there is good connectivity to the coil itself as I did have a ***** of a time trying to get them threaded on.

Thx in advance!

 

[oldboat1]

9.5s are not my specialty, but I think you need to remove the ignition plate to connect from the bottom. Insure the spike is contacting the inner wire (assuming you are using 7mm solid core wires). Following that exercise, set the coil in place making sure the coil mounts are perfectly flush with the mounting posts (should be able to run a fingernail over the joint and find it perfectly smooth). Finally, insure that the spring connector in the plug boot is in solid contact with the inner wire.

 

[Crosbyman]

I have fixed up several and I can't say any generated real hot blue .5 inch sparks... that said for 50-60 year old engines

• remove the mag plate to properly "screw in" the plug wires on the coils
• replace the coil wires anyway with 7mm metallic core wires. I use automotive Belden wires with boots already installed at the factory. Coil secondaries should read rom 4-8 kohms primaries close to 0 ohms
• polish up or replace points and set them at .020 on the high point of the cam lobe. see video link
• If you can't test them for leakage at 300V + ...replace both condensers
• set the plug at .030... or try .035
• disconnect the kill wires...to the front button ...just in case

https://www.napacanada.com/en/p/BMX700175

Testing an Outboard Coil with a Multimeter using an ignition coil from the Johnson H or T

Multimeter testing of Johnson outboard coils

www.pochefamily.org

 

[Bonger6]

All good suggestions fellas and stuff that I'll try....specifically replacing and properly installing the spark plug wires AND aligning the coils. Since that may be a good start to my problem as I don't think I got great connectivity when trying to thread the wires on.

*** oldboat1 - you make a good point on the mounting of the coils. I was being a bit sloppy initially and didn't account for the amount of motion/"play" there could be in the coil mount so I wound up with the flywheel jusssst making contact with one of the coils on the way around. I adjusted but will do so again when I pop everything apart and replace plug wires.

 

[Crosbyman]

don' t forget that 9.5hp pull starters don't spin the fw very fast and resulting sparks may appear a bit weak yet after starting they run fine.

you should be able to screw in the wires on the coil pins at least 3/8 inches

cover with the little boots or insert di-electric grease in the coil pin areas

I just trolled for 3 days and never had a burp or stoppage from my 1966 mdl . I lock it in place and steer with the big fellow