New to me 1972 Johnson 100HP has no spark

[sdjeep]

Hello all,
I have a new to me 1972 Sea Ray SRV 183 with a 1972 Johnson 100HP Outboard, number 100ESL72R. I am new to outboards as my prior two boats were both I/O's. The whole package has been sitting for about 5 years. For the price of free I couldn't pass it up. I'm trying to get the engine running to see if it's a worthwhile project, but there is no spark from the motor. The prior owner is my neighbor and it did run when it was parked. I pulled the plug and cranked it and there is no spark coming from the wires. I don't see any sort of dead mans switch like my 04 Maxum had, but it is acting like something like that is triggered. Cranks fine, good fresh fuel, fresh spark plugs.

I have a repair manual on order, but is may take some time to get here so I was wondering what some common issues with these motors may be that could be cau

 

[racerone]

Top notch battery is required.

 

[sdjeep]

Forgot to mention battery is new and fully charged as well. Cranks over fast, but won't fire.

 

[oldboat1]

Get your neighbor to go over starting procedures with you. (Don't know how literal to read your comment -- If pulled the plug, there won't be spark unless you ground the plug when cranking. Get a tester at an auto supply store if you are testing for spark.)

 

[sdjeep]

Sorry, I need to learn to be more clear. When I pulled the wire, I ran a jumper wire from inside the spark plug wire to about an 1/8 inch from the plug itself and watched for spark between the jumper wire and the plug itself. I know this works for vehicles, but maybe not for an older outboard? My neighbor will be away for about the next 2-3 months due to his work (part of the reason he needed to get rid of the boat).

 

[oldboat1]

think I would get a spark tester. If an adjustable one, you can get a sense of whether there is a spark (1/8 or 1/4 inch if you want), then whether it is strong enough for good operation (about a half inch). You will need a good ground somewhere on the block -- probably know all that stuff. I kind of think you might be having an issue with proper starting procedures for that new boat, but maybe not. I think that is the push button control box -- if so, push the neutral button, and move the shift lever back and forth a little. Also, check out the key switch. I would do the simple sort of stuff first for sure, with a boat and motor that had not been used for a while -- spray some WD-40 or equiv on linkages, a little elec cleaner spray in the key switch -- things like that. Then have at it again. Recalling I had some control box issues with an old '85, but think that was a neutral safety switch connection or similar -- starting circuit issue. Nice rig. If it was working recently, like you describe, should fire up again.

 

[sdjeep]

I went ahead and grabbed a spark tester just to be sure, and I'm also going to get the battery tested. My experience with parts is that just because it is new, doesn't mean it may not have an issue. The engine does crank nice and healthy, but just want to eliminate the possibility of the battery. I won't be able to work on it again until the weekend, but I will also do what you say with the controls and key switch. The starting procedure I have been doing is 1) prime the bulb. 2) Move the lever on the control from run to start 3) Make sure it's in neutral 4) Start while actuating the choke lever under the key just shortly, then trying to crank a few times without the choke.

 

[oldboat1]

sounds right. Think I was describing a diff. control box, though -- yours is not the push button box. There would be a warm up lever to engage.

 

[emdsapmgr]

You could try a test, by disconnecting the red plug-disconnects the control box from the engine. Then use a set of automotive jumper cables direct to the starter from a known strong battery. Let the engine crank and check for spark. If still does not spark, then the problem is on the engine. If it sparks, then the problem is in the control box wiring-even the key switch.

 

[sdjeep]

No Title

Figured a few pics might help to show what I'm working with. One is on the back of the motor, one is the cover on the electrical (with half the wire key gone)and the other is the style of control box I have. With the park plug tester there is still no spark. What is the red plug you are referring to to disconnect to test?

 

[sdjeep]

Also, checking the wiring diagram in the Top Secret Files section, I see there is a 20 amp fuse from the key switch to the starter solenoid. Would this most likely be in the fuse block under the dash, or is there another somewhere? The starter does engage and crank and I assume if this fuse was an issue it wouldn't.

 

[boobie]

This motor has no red plug and is battery cd so the ignition switch has to be in the system to feed the amplifier so no disconnecting. Check the wire going to the amplifier to make sure it has 10 volts when cranking. If it does you could have a bad amplifier, coil, trigger or cap and rotor.