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Mercruiser 3.0 no spark

T

Tom Maslar

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I have continuity with ground on the purple wire at the neutral safety switch. I also have no power on the purple wire to the coil. I am getting no spark.
 
The neutral safety switch is in the remote control box. It has 2 yellow w/red wires & has nothing to do with ignition. It strictly controls starter operation.
I believe you are looking at your shift interuptor switch.
 
I have power to the ignition switch and the motor turns over. When I remove the electrical plug on the coil that has the purple wire, turn key to on position, I get one volt. When I disconnected the leads on the shift interrupter switch it shows continuity tone on a multimeter when the lever is pressed. The purple wire that goes to the shift interrupter switch shows continuity to ground when it is isolated from the shift interrupter switch for testing.
 
The shift interuptor switch should not be depressed except momentarily while shifting out of gear. In other words, it should be centered in the base of the V with clearance so the plunger is not touching. If the fork is depressing it while in neutral you have a cable or adjustment problem.
 
Yeah, I know that, lol. I depressed it when attached to a multimeter set to tone continuity to test that it functions. I got a tone, so it functions when depressed. Sorry for the confusion but these things can be difficult to explain.
 
Tom Maslar said:
I have power to the ignition switch and the motor turns over. When I remove the electrical plug on the coil that has the purple wire, turn key to on position, I get one volt..
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What is the motor serial number or what year is the boat.

Sounds like the kill switch has been pulled, or it's gone bad

Neutral safety switch just keeps the motor from cranking if not in neutral. Your motor cranks so that's not the issue

You mention continuity but need to know voltages. Key switch purple wire with key ON should read 12V
 
Funny you should say that. You are close. I stumbled on the solution today after pouring over schematics, forums etc., for almost 10 hours. Its a 1992 Rinker 181 Withe Delco Est, most likely added later by the first owner. I bought it in 98. The air cleaner says digital electronic ignition. I traced power continuity from the dead man switch and the ignition. Then there is a plug where yellow goes to Red. It contains two other wires, one blue. I pulled the plug apart and corrosion fell on my face. I put it back, cleaned and got almost 12v at the coil. When I replaced the feed to the dead man switch my voltage went up to .50 volts less then at the battery. Problem solved. The big issue for me was this failure took place at the exact time I replaced the alternator. I am all good!
 
Tom Maslar said:
Funny you should say that. You are close. I stumbled on the solution today after pouring over schematics, forums etc., for almost 10 hours. Its a 1992 Rinker 181 Withe Delco Est, most likely added later by the first owner. I bought it in 98. The air cleaner says digital electronic ignition. I traced power continuity from the dead man switch and the ignition. Then there is a plug where yellow goes to Red. It contains two other wires, one blue. I pulled the plug apart and corrosion fell on my face. I put it back, cleaned and got almost 12v at the coil. When I replaced the feed to the dead man switch my voltage went up to .50 volts less then at the battery. Problem solved. The big issue for me was this failure took place at the exact time I replaced the alternator. I am all good!
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if it says Digital Electronic ignition on the flame arrestor cover it means it had the EST from the factory. 3.0s have used EST since the early 90s

Where were the wires on this connector going ? Looks like someone wired something in on the red which is 12v positive power supply
 
No, it was a brittle factory plug and had blue, orange and purple. Sorry, if I miss spoke. Purple is part of the ignition circuit and excitation takes place at a confluence, near the transom, downstream. Orange indeed plugs to red and enters fuse box at 20 amps . Again, sorry if I got any of that wrong from memory earlier. I redid the connections in 10awg marine tinned in ancor companies wire. Im very happy to have found the schematics online. This took a very long time, im usually much quicker to diagnose. Thanks for all your help.
 
I believe distributorless ignition was used 90 to 94 on some models, or 89 to 93..not sure. Anyway, silly not to just write delco Est. I put that on with a label machine for the next guy or me in 6 months...lol.
 
Tom Maslar said:
I believe distributorless ignition was used 90 to 94 on some models, or 89 to 93..not sure. Anyway, silly not to just write delco Est. I put that on with a label machine for the next guy or me in 6 months...lol.
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yes there was a DDIS. I had a 1990 3.0 LX with it, if i recall the flame arrestor cover read Digital Distributorless Ignition System vs Digital Electronic Ignition. Its been years so I may be off and splitting hairs. I never had an issue with the DDIS but it only hung around a couple of years and most parts were NLA...

You Would see if someone replaced the DDIS with EST - there would be splices in the engine harness to wire it up.
 
Im surprised it is not plug and play to adapt? Thanks for the info. I learned a ton about my boat figuring this out. I already taught myself to do the gimble, u-joints, bellows, shift cable etc. Just one more piece to the puzzle. Repair on long island is unavailable for old boats like mine. Guys wont touch them. This ol gal does 39mph and is a regular on the fire island inlet fishing scene. I am almost always the smallest vessel out there and I get a lot of second looks, but the fish could care less.
 
Tom Maslar said:
Im surprised it is not plug and play to adapt? Thanks for the info. I learned a ton about my boat figuring this out. I already taught myself to do the gimble, u-joints, bellows, shift cable etc. Just one more piece to the puzzle. Repair on long island is unavailable for old boats like mine. Guys wont touch them. This ol gal does 39mph and is a regular on the fire island inlet fishing scene. I am almost always the smallest vessel out there and I get a lot of second looks, but the fish could care less.
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it is plug and play relatively except for where it get power, shift interrupt, and tach signal from the existing harness. if you are converting a older points system you need to bypass the resistance wire. But make no mistake the EST is a robust OEM quality set up. if the original harness was set up for an EST it is 100% plug and play, as both VP and MERC used them as OEM. Its also available as a retro fit for points replacement, or to replace the distributorless ignition, or where the ignition module ($$$) on a Merc thunderbolt dies

yeah especially in salt water a lot of guys don't want to work on older stuff. Add a few broken fasteners to every job, its not good for customer or mechanic.... that's why most of us are here.
 
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