Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

[razopp]

Hello,

I bought a 1973 Johnson 20 HP Seahorse (73R20A) in late December. The motor started right-up (2nd pull) and ran great in the tank. We let it run dry to prevent the carb from gumming up knowing it would not be used for a couple of months. I tried starting it last week and below is the sequence of events. It will not start right now. I bought new fuel, fuel line w/bulb, and fuel lines for the motor. The fuel in the motor is mixed at 50:1 per the instructions and also has the Stabill Ethanol treatment. The fuel is currently two weeks old. When trying to start the motor, the tiller is on the start position and the fuel vent on the tank is open.

I went to run it last week and the fuel pump had cracked at the input fuel line from the tank. I replaced the fuel pump with Sierra model 18-7350 I believe. I bolted this right on. Please see picture below of replacement.
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I also put new spark plugs in it (Champion J4C which were stock with this motor). The previous owner had used J8C. Any idea why someone might use hotter plugs? The plugs have always stayed dry when trying to start.

I also verified I can pull the starter rope with the plug out and see a blue spark when grounded against the block on both plugs. So, I assumed per the Johnson manual the electric circuits were good. The book only tells you to test the coil and magneto if there is no blue spark.

It still would not start. The fuel bulb on the tank was holding pressure so I took the carb off and checked the bowl. There was no varnish and it already had the upgraded plastic float bowl installed which was not sticking at all. All the gaskets looked good and it appeared it had been recently rebuilt. I went ahead and sprayed carb cleaner on it through all the orifices and remounted it.

I then looked over the trouble shooting and read some web posts and found these units are prone to cracked coils. Below are pictures of my motor and coils. I have not redone the points or condensers as the motor started right up in December. I am not sure if I should run some sort of test on these or the magnetto/coils/condensers. Any reference you can point me to on how to do this as the manual I have is pretty vague.

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Do you have any suggestions on where to go from here? I don't want to just start replacing stuff without knowing if it is bad.

Thank you very much for any assistance?
Robert

 

[Daviet]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

Some people run a hotter plug if they do a lot of trolling, but a J8C is to hot, use a J6C.
You need to check spark with an air gap tester, the spark should jump a 7/16" air gap and be bright blue.
Try squirting some fuel mixture into the carb and see if it will start, if it does you have a fuel problem.
The coils looked cracked to me and should be replaced. A cracked coil can still work, but might break down under load and moisture will get into them sooner or later.

 

[razopp]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

Thank you for the feedback. I shoudl add there are visible hairline cracks through the outside of both the blue coils. I assumed they were cracked after looking at them, but is this significant enough to cause it not to start now? I tried putting starting fluid into it and it would fire and rumble (0.5-1 second) and then die. I thought it might be fuel too, but don't know where to start. It sounds like a should do the coil, tune-up kit, and rebuild the carb. Do you agree?

Also, where does one find an "air gap tester". I found ignition testers, but they all appear to be lights at Harbor Freight and Autozone.

Thank you again,
Robert

 

[Daviet]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

I would get it running first, fix one problem at a time.
You shouldn't use stsrting fluid, no lube in it for the cylinders.
I think some auto parts stores carry them, at least around here auto zone does.
If you can't find one you can try and insert a phillips head screw driver into the spring inside the boot that snaps over the plug end and hold it 7/16" from a ground. Make sure it's an insulated screw driver.
If it will fire if you squirt fuel into the carb, you have a fuel delivery problem. Pull the fuel hose going to the carb and pull the engine over, does fuel squirt out of the hose? Remove the 7/16 drain screw out of the bottom of the carb bowel and pump the primer bulb, does fuel run out of the drain, if so you are going to have to pull the carb and clean it and put a kit in it.

 

[razopp]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

Thank you for the plan. I bought the air gap tester at Autozone. I will test it tomorrow or later tonight and check back. The air gap tester I bought is the OEM model that is called and adjustable ignition tester.

 

[Daviet]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

That should work for you, adjust it to 7/16".

 

[razopp]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

I pulled the plugs to run the test and the largesy gap in either cylinder that I could get a spark to jump is about 3/16th". I assume this means I have an ignition issue. Any suggestions on where to go from here? I assume I need to test components of the system. I believe my manual says to test the coils, magneto, and stator. Does this sound correct?

Thank you,
Robert

 

[kodibass]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

Yep'

 

[razopp]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

Is therea thread or link someone could post that might show me jow to do these tests? I only ask as my manual cobers several models and to be honest, I am not the best with a multimeter.
thanks,
Robert

 

[AlTn]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

I think youtube has one titled ..testing < maybe antique ?> outboard ignition coils..or something like that...do you have flywheel puller? a harmonic balancer pulley will do...you'll need 3..1/4 x 20 Grade 8 bolts < the ones I have are 2 x 1/8" long with about 3/4" of it threaded > as well as some Grade 8 washers...the ignition you have is prone to grounding issues and both sets of points need to be really clean as well as all grounding points for the coils, etc.

 

[razopp]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

I'm back again. First I want to say thank you as this has been helpfuln so far. I tested the continuity on the coils with my multimeter and had the following results.
I have Continuity between primary on both coils. There is also about 6 ohms resistance on the secondaries of both (at the 2000 setting on my MM).

So, I took the advice from above and squirted fuel into the carb. It started up and idled a second beforeI hit the kill switch (it was not in a tub of water.) I know I do not have enough spark based on the air gap test and the coils each have one crack each.

My question is should I focus on the fuel issue first and deal with the weak spark after I figure out the fuel issue?

 

[kodibass]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

I like to go the other route, first make sure the ignition is up to par, then the fuel system, the fuel system just seems easier to get tuned in & adjusted once you are able to get it to run even for short periods, but that's just me.

 

[razopp]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

Thanks. So you woud recommend replacing the coils and then doing the fuel issue. Is that correct?

 

[tx1961whaler]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

I'm not sure an 18-7350 will run upside down like it is mounted. Is there a marking on the fuel pump body that says "Top"?

 

[82rude]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

if i read correctly you said you had hairline cracks in on the coils.replace, without a doubt.

 

[razopp]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

Thank you both for the feedback. I will replace the coils as they both have cracks through the blue insulation.

Thank you,
Robert

 

[razopp]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

Thank you for the comment. I wondered that as well. The output is on the top of the pump. The problem I was having was that when the output to the carburetor is put in the down position the fuel line was pinching. I will reverse it again and see if that helps. I do know that I tried unhooking the fuel line to the carb from the pump and when I pulled the motor over very little fuel came out. I will reverse the pump and try that now too.

I'm not sure an 18-7350 will run upside down like it is mounted. Is there a marking on the fuel pump body that says "Top"?

 

[razopp]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

I have another question. I looked at the coils on iboats and it said I need two of the coils (shown above in the photo) and 1 of another coil that looks as though it may be under the flywheel. Do I have to replace all three at the same time or just the two mounted to the exterior of the motor?

Robert

 

[the machinist]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

I believe the 7/16" spark jump is for the electronic ignition, most old time mechanics are happy if they get 1/4" on magneto ignition.

 

[Daviet]

Re: Are these coils cracked? - 1973 Johnson 20 HP Seahorse (Won't Start)

You can replace the two external coils without replacing the coil under the flywheel.