1969 Johnson 9.5 Misfire

I just acquired a 1969 Johnson 9.5. It's misfiring pretty bad. It starts fine when choked and when I hold the choke half out, it seems to run fine. It gets worse as it warms up. The fuel filter is going empty as well. I've replaced the fuel lines and spark plugs and have also clamped the fuel line directly from the priming bulb to the fuel pump with no luck. I have a gut feeling I'm sucking air and it's going lean but I can't prove it. I tried spraying some carb cleaner around the carb and fuel pump when it's running but I'm not noticing any difference in how it runs. I'm thinking about rebuilding the fuel pump and possibly the carb but I want to make sure I'm barking up the right tree. Any ideas?

Does spark jump a gap of 5/16"on a test device , yes or no ?--Perhaps check the plug wires where they come down out of the magneto plate.-----Common to crack at the 90 degree bend there.------Having to hold the choke out indicates the carburetor high speed jet may have partial blockage.-----Normal for some filters to run empty on these motors from the 60's.

I will check the spark and plug wires this weekend. I'll let you know what I find. Thanks for the info!

Ok, one of the plug wires is jumping 5/16, the other isn't. It won't even jump 3/16. I'm ordering a pair of coils and some plug wire right now. Hopefully that fixes it. Thanks again for the help!!

Get some points and condensers at the same time.

So, here's where I'm at. I've replaced both coils, plug wires, points, and condensers. Points are gapped at .020 when pointing at the key for the flywheel. I've disconnected the kill switch wires at the points. Plug wires are copper core 7mm wires sold for tractors at Rural King. I now have no spark from either wire. Coils are lined up flush with the boss/mount. I ran out of time but will check resistance when I start on it again. Any ideas? I have a hard time believing I have 2 bad coils but I can try putting the old coils back in. What am I missing? It's a simple system!!

I have to ask you where you live and where the motor has been run? Like....what state? I have replaced many crankshaft seals on these poor little motors....usually the upper seal. Why? I can't say for certain, but I suspect ethanol.

Did one some years ago where the cam had been installed upside down.-----New points may still have to be cleaned.-----Wires from the coils going to the correct set of points.----Be an easy fix for me if motor was on my work bench !

I have no idea what "Points are gaped at .020 when pointing at the key for the flywheel" means, unless you've set them properly as mentioned below. If you haven't set them as follows, do so.

Point Setting:
Have the flywheel key aligned with the fiber rubbing portion of the points.
Set the points so that a .020 gauge will slide thru BUT a .022 will not.

Coil wire installation:
The pointed contact inside the coil wire hole is not just a pointed spoke... it is a spiral machined spoke, and as such, the spark plug wire is to be inserted with a bit of WD40 to act as a lubricant, then inserted into the hole and onto that spoke in a clockwise twisting action... pushing and twisting until resistance is felt that you are aware that the wire is screwed on as far as it should go.

Coil installation:
The small aluminum towers that the metal portion of the coil sits upon... notice at the top of those towers a slight bevel there. The upright metal portion of the coil must align with the inside top portion of that bevel to give the coil the proper clearance between it and the flywheel magnets.

Boot and wire to spring connector assembly:
The rubber boot, spark plug end.... With the wire cut to the length required, trim back 1/4" insulation again but do not solder tint the wires. Simply fan out the wires and fold them back against the insulation, cutting the excess off. Holding the spring wire terminal, estimate where the prong should be inserted so that the spring will be flush against the exposed wire. Hold the spring terminal away from the wires end (sideways) and insert the prong into the insulation and into the center wire, then swing the spring terminal in front of the exposed wire portion (makes a tight fit for continuity purposes). Spraying the inner portion of the boot where the wire will insert with a small amount of WD40 makes the installation of the wire a easy project.
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That setup should give you proper spark.

Proper spark plugs would be Champion J6C plugs gaped at .030 .

I had a bunch of information added to my post, but when I turned the phone I lost my draft. So here we go again.
Do you live or has the motor operated in the state which has mandated ethanol? These little motors have a pure rubber crankshaft seal which is easily destroyed by ethanol. I have changed many of these crankshaft seals usually on the upper cylinder. Why? Because it allows an excessively lean mixture into the upper cylinder and will cause an overly lean symptom, called a "hickup". You will notice the upper spark plug will run a much lighter color. Then eventually top cylinder will dry out and score itself and the motor will become a parts motor. I have no less than 15 of these 9.5 in the back of my shop. Minnesota is a heavy ethanol State and ethanol fuels have destroyed many of these little motors.

Thanks for the info guys. As far as where I live...Indiana. We do have some ethanol in our gas. I'm witnessing a definite lack of spark. I haven't researched the crankshaft seal issue. Are there some more symptoms I can look at to verify whether that's an issue or not? Should a lean burning plug be grey, or just a little lighter than the other? Neither of them looked abnormal when I replaced them.

As far as gapping the points, it sounds like I have done it correctly. The flywheel key in the crankshaft is pointing at the cam follower of the point when I'm adjusting each of them. All the other adjustments also seem correct.

I did some more troubleshooting today. The new coils give me no spark. I measured 7,000 ohms from the plug wire to ground on both plug wires...exactly the same as from the pin of the coil to the ground wire. I put the old coils back in and have spark again. I'm measuring 3,300 ohms on both of those coils. One wire is giving a stronger spark than the other, however. It sounds like I may have received the wrong coils? The coils I got say they're a replacement for OEM number 584477. I'm thinking i should return the coils.

Those coils will interchange, the impedance might be different but they will work. Could there be a short to ground through your kill button? The symptoms of a lean burning motor would be the tendency to hiccup at low speed or idle along with the inability to dial it in with the low-speed adjusting needle. A clean-burning plug will be a light tan. The proper color would be a medium to dark tan but could run a little darker if the motor has been trolled or run at low speeds for a longer timeframe. Much depends on your oil type and oil mixture. Since I personally run Amsoil at much leaner mixtures I rarely get a plug that is really dark brown.

Does the motor run better with the cover removed??? Some of these motors tend to develop an under the cover exhaust leak.

Timguy, I disconnected the kill switch wires right at the points so grounding shouldn't be an issue. As far as a lean burn, I'll look a little closer at the plugs and post a pic of I'm not sure. My gut is telling me I'm burning lean. But I know for a fact I have a spark issue as well. One wire is definitely sparking hotter than the other. You say the new coils should work but why would they both give no spark? I hooked them up the same way as the originals and the connections were all good.

Bobbyc, I've only run it with the cover off. I haven't even tried with it on. This motor was just given to me a couple months ago.

Are you sure you got the plug wires spiraled all the way into the coils properly. Most coils actually have a little screw inside that will burrow into the core of your plug wire.

Yeah, I did. Resistance from the plug wire boot to ground was the same as from the ground wire to the screw pin when I removed the coil. I was pretty careful to make sure I had good connections.