1988 20 hp Mariner (NO Spark)

skip44820

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Where to start on trying to identify no spark problem on a 20 HP Marine 2 stroke, I have been going thru old posts and don't see anything that tells me where to start. I just ordered a service Manuel but patience gets the best of me, besides it cold where I live and not much to do, any help is appreciated. Guy that owns the motor says that spark comes and goes. One minute he has spark next minute its gone. Thanks
 

QBhoy

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Hi,

I would check the continuity of the plug leads first off. Check they are within the usual ohms range for that size of lead. I would also say that if she is like a fair chunk of 20hp mariner engines of that era...and has a manual pull start...it can be a hit or a miss if you are able to achieve a contact from plug to a clean earth...hold it there..get a good visual on it...and at the same time, manage to pull the starter chord without messing things up.
If you have checked the leads, changed the plugs already...I might be tempted to get a socket on the flywheel and turn her over with a driver or drill..carefully of course.
 

skip44820

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Hi,

I would check the continuity of the plug leads first off. Check they are within the usual ohms range for that size of lead. I would also say that if she is like a fair chunk of 20hp mariner engines of that era...and has a manual pull start...it can be a hit or a miss if you are able to achieve a contact from plug to a clean earth...hold it there..get a good visual on it...and at the same time, manage to pull the starter chord without messing things up.
If you have checked the leads, changed the plugs already...I might be tempted to get a socket on the flywheel and turn her over with a driver or drill..carefully of course.
Out of all the electrical things on the motor why would you check the wires first? Have you had a similiar problem with this motor. Also does this year motor have a bad history? And thank you
 

QBhoy

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Out of all the electrical things on the motor why would you check the wires first? Have you had a similiar problem with this motor. Also does this year motor have a bad history? And thank you
Hi there,
Just a couple of reasons really. Maybe mostly because I wasn’t really sure of how savvy you might be around these kind of things in general and maybe it always being. Tough one to diagnose without being there in person.
Another really good reason is because I’ve had and still have just far too many 2 stroke engines from this decade, the one before and the couple after too. Outwith serious abuse and/or misuse, anytime they actually do go wrong…it’s 99 times out of a 100, something very simple.
I’d say that most guys that have been around these things for decades, would tend to agree.
Another reason might be that apart from anything else, it’s a good idea to start with the simple things first…rule them out, before things start getting very invasive, like taking flywheels off to look at stators and all that.

Its likely unfathomable to even count how many times some guys (including me and all the rest here) have went far too deep into tearing things apart..when all the issue or fault turned out to be, was a spark plug, fuel, carb clean or similar. Or perhaps in this case, a HT lead broken, shorting or boot failure.
Even things like the stop switch or lanyard (if she has one) wiring. Common thing too.

So your engine is probably just after or about the crossover time between Yamaha and Mercury. She’s likely a Mercury I’d think. Either or…both were very good engines. The Yamaha maybe slightly preferable perhaps.
Very reliable either way.
 

skip44820

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The spark plug leeds test ok. I put new stator on cause the org. tested low. Thought for sure Id get spark but not today Trigger is next. Im not real sharp with the ohm meter but I have to get this running. Any other help is appreciated
 

QBhoy

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The spark plug leeds test ok. I put new stator on cause the org. tested low. Thought for sure Id get spark but not today Trigger is next. Im not real sharp with the ohm meter but I have to get this running. Any other help is appreciated
Sorry if I missed it previously, but how are you trying to prove a spark ? Do you have a spark tester plugged into the lead or something similar ? Or are you just trying to hold it against an earth on the engine maybe ? Not always a reliable way of doing it, if the latter. I find anyway. Did you test the continuity of the HT leads with and without the plug in place ? What readings did you get ?
Have you tested the stop switch for health ? I just recently had no spark on a wee Yamaha 2 stroke engine. Had the points in bits and all that. Still no spark. Ended up being the stop switch
 

skip44820

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Sorry if I missed it previously, but how are you trying to prove a spark ? Do you have a spark tester plugged into the lead or something similar ? Or are you just trying to hold it against an earth on the engine maybe ? Not always a reliable way of doing it, if the latter. I find anyway. Did you test the continuity of the HT leads with and without the plug in place ? What readings did you get ?
Have you tested the stop switch for health ? I just recently had no spark on a wee Yamaha 2 stroke engine. Had the points in bits and all that. Still no spark. Ended up being the stop switch
I am mobile right now. I don't have my wiring diagram in front of me. When you say stop switch, is this the same as ignition key
 

skip44820

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I am mobile right now. I don't have my wiring diagram in front of me. When you say stop switch, is this the same as ignition key
Also, spark plug wires. I'm not really sure how to test the wires. I put the red probe in the end of The Wire. I put the black wire on ground on the block. Is that correct?
 

QBhoy

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I am mobile right now. I don't have my wiring diagram in front of me. When you say stop switch, is this the same as ignition key
Yeah. If that’s what you have..yeah. Test that and the lanyard safety chord switch if you have one
 

skip44820

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Yeah. If that’s what you have..yeah. Test that and the lanyard safety chord switch if you have one
I'm not sure I know how to test the switch, I'm looking over the electric start wiring diagram and I'm drawing blanks
 

Faztbullet

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Neutral start interlock switch. Can I remove that and bypass it?
This has nothing to do with ignition. The switchboxes on these have a high failure rate
 

QBhoy

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Neutral start interlock switch. Can I remove that and bypass it?
Not sure that may affect things in the way you are having. At least not perhaps on that system.
But almost certainly, the lanyard kill switch will stop any ignition (spark) if it’s intervening.
Depending on what type of harness and or remote throttle box you have. If it’s active, this can result in the engine cranking over on the key…but despite that, there will be no ignition allowed at all.
Send a picture of your remote control throttle box up at the helm. From the side and looking towards the ignition key barrel too. We might be onto something here.
Or at least we can go from there. Yes you can test the stop/kill circuit and you can by pass it too.
The in gear interlock most likely (if you have it) or most usually, doesn’t allow you to crank her over in the first place. Not exclusively, but usually.
 

skip44820

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Not sure that may affect things in the way you are having. At least not perhaps on that system.
But almost certainly, the lanyard kill switch will stop any ignition (spark) if it’s intervening.
Depending on what type of harness and or remote throttle box you have. If it’s active, this can result in the engine cranking over on the key…but despite that, there will be no ignition allowed at all.
Send a picture of your remote control throttle box up at the helm. From the side and looking towards the ignition key barrel too. We might be onto something here.
Or at least we can go from there. Yes you can test the stop/kill circuit and you can by pass it too.
The in gear interlock most likely (if you have it) or most usually, doesn’t allow you to crank her over in the first place. Not exclusively, but usually.
I brought the
Control box back by motor and checked continuity in 6 wires.
Not sure that may affect things in the way you are having. At least not perhaps on that system.
But almost certainly, the lanyard kill switch will stop any ignition (spark) if it’s intervening.
Depending on what type of harness and or remote throttle box you have. If it’s active, this can result in the engine cranking over on the key…but despite that, there will be no ignition allowed at all.
Send a picture of your remote control throttle box up at the helm. From the side and looking towards the ignition key barrel too. We might be onto something here.
Or at least we can go from there. Yes you can test the stop/kill circuit and you can by pass it too.
The in gear interlock most likely (if you have it) or most usually, doesn’t allow you to crank her over in the first place. Not exclusively, but usually.
Tested continuity from control box to end of cable with male connectors. yellow red stripe, yellow blk stripe,blk with yellow stripe,blk, red,tan, they all had continuity. So does that mean the problem is on the motor. I got a switch box coming tomorrow. Ready to tear hair out. Thanks for sticking with me
 

skip44820

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I brought the
Control box back by motor and checked continuity in 6 wires.

Tested continuity from control box to end of cable with male connectors. yellow red stripe, yellow blk stripe,blk with yellow stripe,blk, red,tan, they all had continuity. So does that mean the problem is on the motor. I got a switch box coming tomorrow. Ready to tear hair out. Thanks for sticking with me
 

skip44820

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Faztbullet

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Disconnect the blk/well at pack and test, if spark wiring issue. No spark ignition issue.
 

QBhoy

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I’d make sure the toggle (kill switch) under the ignition barrel, is all the way up and not activating. Test the wiring there.
Some of it looks a bit corroded or dry/brittle in places perhaps.
Listen. It could be at the engine…but for sure, issues in that box will cause no ignition. The ignition wire itself too. The yellow and red wire…and its circuit..check all that out for health. Both ends.
 
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