J90TCLTE After Coil Replacement

[Behemoth]

Hi all! First time poster here. I have this 90hp from 1983. I got this as a project last year and have had it out on the water a few times. I wanted to start documenting my process through video and get some opinions from everyone here.

When I got this the coils were rough looking. 1 had failed test completely and the rest tested fine. I replaced 2 of the coils. The one that failed and the next worst looking one. I finally got her up and running. Now I decided to replace the last 2 after redoing the carbs and letting her sit for a few months. I really didn't like the way they looked even though they tested fine. After the carb cleaning she was giving me a hard time to start after a few fishing trips but always got me back to the launch.

Today an swapped those last 2 coils. Coil #1 and #4 and she starts up like never before.

My question here is I noticed that there is a slight dip in RPM every so often. Similar to when I activate the primer at idle. Is this a moment where it is running rich and it just catches back up? Granted the video I took this is probably not warmed up very well. I put a little video here if anyone can take a look and give me suggestions. As you see at the beginning I have the whole entire manual so if I can get some opinions on how she idles on the muffs and anything else I should consider before tossing her back on the water I would be grateful.

Idle & Startup after Coil Change 9/17/18 - Johnson 90hp V4 1983 Crossflow J90TLCTE
https://www.youtube.com/watch?v=S9i54VZWNWE

 

[flyingscott]

Well the first thing is you are running on muffs. Idle must be set with the motor running in gear and warm. Did you make sure the switchbox wires are running to the correct cylinders.

 

[Behemoth]

Well the first thing is you are running on muffs. Idle must be set with the motor running in gear and warm. Did you make sure the switchbox wires are running to the correct cylinders.

Well the first thing is you are running on muffs. Idle must be set with the motor running in gear and warm. Did you make sure the switchbox wires are running to the correct cylinders.

Yes. I have set idle per the manual out on running water. I get the same dip the only difference is my RPMs are lowered to spec per the OEM manual.

I also verified Blue and Orange are top cylinders (sky) and the bottom are flat color. I verified this from the coil replacement directions and reviewing the wiring diagram in the back.

For clarification the little rpm dip still happens in the water with back pressure.

 

[Behemoth]

By out on running water I mean in forward gear at idle in the middle of the lake.

 

[Behemoth]

Any other thoughts here? Anything else I might look for that isn't in the manual that comes from experience?

 

[Charlie5653]

Just an observation from your video -- it looks like your cam is not center on the carb roller. Ensure that the carb butterflies are completely closed for idle

 

[Charlie5653]

one other thing, I see an in line filter -- see if any small bubbles show in that filter when you prime the bulb

 

[F_R]

I must be getting numb. I don't see anything wrong with the way it is running. Maybe a missed beat right toward the end.

 

[Behemoth]

Just an observation from your video -- it looks like your cam is not center on the carb roller. Ensure that the carb butterflies are completely closed for idle

Good eye. I do plan on verifying link and sync and timings tomorrow as I haven't been able to tonsinct removing the flywheel. If my new gas can has bubbles in the filter what will that mean? I'm not going to be running on that old one from the video any longer.

 

[Behemoth]

I must be getting numb. I don't see anything wrong with the way it is running. Maybe a missed beat right toward the end.

I might be too anal about a motor this age. It's my first and I brought it back from death so I'm not super sure if it's to be expected to have little things like that. I can live with it if someone with experience thinks it sounds fine.

 

[Charlie5653]

Well I'm not a pro by any means however, I have had pretty much experience with a motor close to yours to share in recent weeks.
My suggestion would be get to the water and run it for a couple hrs warmed up. Get on top of the water and clean those carbs out a few times. Idle around some. Just keep mixing it up for a couple hrs and pay attention to characteristics

My opinion is muffs are pretty much a waste for troubleshooting . If you can get a barrel and fill it, that worked so so much better for me. (at least some back pressure anyway).

My 115 hp had set for 12 yrs in a barn. When I drained the boat fuel tank I had put on a little in line filter (like I saw on yours) to ensure the tank was clean.

After a couple weeks of trying to get rid of an idle miss I had noticed every time I primed the bulb little air bubbles were bubbling into that clear filter. And since I had run 15 gal or so thru the tank with no dirt appearing I was comfortable removing that filter.

I removed the filter and replaced the short fuel line going to the tank and the idle miss was gone. ( a little unwanted air just crush the idle on a 2 cycle.

I also think the seafoam decarb works well

Cheers

 

[Charlie5653]

Oh, and I dont see any advantage to removing the flywheel if thats what you were saying. Your problem (if any) is not under there.

 

[Charlie5653]

The best advice I received on this site was to purchase a good spark tester. !! One that adjust, not those crap light things. I hope you have one . It is one of the first tools needed and handy to have... and compression test each cylinder.

But your motor sounds pretty good on utube. So if anything --- a really really small air leak or a trace of carbon/trash that seafoam would probably eat up..... would be my guess

 

[Behemoth]

Oh, and I dont see any advantage to removing the flywheel if thats what you were saying. Your problem (if any) is not under there.

Oh not I had to remove the flywheel to clean and oil the timerbase because some gebius greased it. I had run it for a year on the water and I'm just trying to chase down any last few issues I might have before fall boating season. That's really nice around here.

Thanks for the help.

 

[Charlie5653]

welcome mate, best of luck !