90 hp Johnson won't start - advice?

[gbarrett]

My pastor has solicited my help with his 90hp Johnson motor. It did run about a year ago, but after sitting idle for too long, it won't start. I'm used to working on inboards so I'm not familiar with this engine.
I've checked spark, it's there, but not as bright or hot as I'm used to seeing on other engines. Is that normal?
We've got fuel, and used starter fluid. It will hit a time or two, but never any more than that.
I haven't put my compression gauge on it yet, but it feels consistent.
If I advance the timing, the motor will seem to "hang" until I ease the timing back. So I would guess it is trying to spark?
I cleaned each of the contacts on the terminal strip as well as the contacts on the coils.

I'm sure I'm missing something obvious, I just don't know what to look for. Thanks in advance for the help.

Greg

 

[Chris1956]

Re: 90 hp Johnson won't start - advice?

Greg, It could be several things (clogged carbs, incorrect timing, weak spark, low compression). That motor is fairly sophisticated, so the problem may not be easy to find, especially for someone unfamilar. I recommend a compression check, followed by another spark test. The spark should jump a 5/16" gap and look a nice blue. Post back.

If the compression is good, it is likely a service manual needs to be employed to further troubleshoot and repair.

 

[eavega]

Re: 90 hp Johnson won't start - advice?

You might also want to specify model/year of motor. That would help in trying to determine where to go once you do a compression test. You may not want to start your motor with starting fluid as that is missing the essential lubrication. Other than that, the typical "sitting around" motor problem will be dirty carbs, especially if it was left to sit around with unstabilizied fuel in the bowl. there is a thread in the "Top Secret Files" that you should look at "Awakening a sleeping outboard"

Rgds

 

[gbarrett]

Re: 90 hp Johnson won't start - advice?

I don't think there's a snowball's chance in Miami that the spark would jump 5/16". I'll get a spark doohickey and check that. I was hoping it was a just one of those things that everyone knows about.

I'll keep ya posted.

 

[gbarrett]

Re: 90 hp Johnson won't start - advice?

Ok, ran some tests:
Compression: 3 were 100, 1 was 110
Coils - power to ground 0 ohms all coils
Coils - spark to ground 254 ohms all coils
Key-on, no voltage on the input side of the coils - probably normal for this engine. I have no way of testing the pulse from the power packs.
Spark won't make 5/16" any coil

Couldn't find the manufacture's tag on the engine, but the block number is: 132290 05F 01

So, if I were working on a regular car or inboard engine, I'd suspect the coils are bad.

 

[Chris1956]

Re: 90 hp Johnson won't start - advice?

Greg, OMC made 90HP motors from the mid-sixties until now. They went thru several ignition styles. Most would not have voltage at the coils with the key on. Can you post a picture?

BTW - the compression is good. Also, good coils would read less than one ohm, across the primary winding to ground. Perhaps your meter is not that sensitive, so it shows a dead short.

 

[boobie]

Re: 90 hp Johnson won't start - advice?

Four coils don't go bad at one time. Sounds more like a bad pack if we're guessing without testing properly.

 

[gbarrett]

Re: 90 hp Johnson won't start - advice?

I'll get back over there to work on it in a couple of days. I did find out that my pastor had someone else work on the motor last spring to work off some debt (the guy was a self-confessed novice). That explains some of the things I've found. Also, I found another semi-complete 90 HP Johnson laying in the back of the garage that he was using for parts. Now I have no idea what year I'm working on. There was also a plastic bag full of cut wires and plugs laying next to the donor motor. Hopefully I can sort through this mess.

I'll keep y'all posted. Thanks for the help!

 

[gbarrett]

Re: 90 hp Johnson won't start - advice?

I still have no idea what year motor this is. The block is not original to the rest of the motor and there is no tag. The block-plugs are no help either as it looks they have been replaced at some point. I've attached a few pix to see if anyone can provide an educated guess about it.
Also, the plug wires are shot - no electrical connection, the ends corroded off. I'm making new ones later today.

 

[blimp]

Re: 90 hp Johnson won't start - advice?

Looks VERY similar to my '87 90hp, I would guess late 80s.