1996 Cobalt 220

[chelanfan]

Thank you for this forum it has been very helpful over the years. I have owned my 1996 Cobalt 220 since 2014 and love my boat. It has the 5.7 Magnum thunderbolt engine that's been great and for the most part easy to maintain. This past weekend I had to be towed for the first time as the boat just shut down without any warning. I have no spark to the plugs. Last winter I changed the distributor cap, rotor, plugs wires, coil and sensor assembly in the distributor. The boat was running great. The night before we did have 5 inches of rain and everything was saturated. Talking with the local boat shop mechanic explaining my situation he asked if I had checked the ignition switch and the small breaker next to the ignition switch. My question is what else could it be? The ignition switch has 4 terminals on the back and has 3 positions - off - on - spring loaded start.If anyone can help with a part number that would be great. As far as the breaker goes it's an E. T. A. series 1658 but does NOT say what amp it is. If anyone can tell me what amp breaker it is I would greatly appreciate it. Thank you in advance.

[AsLan7]

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Hey CF. Welcome to the CoblatChat forum. So glad you found us!

Thanks for posting pics too. Even the coveted engine shot!

This may be a dumb statement & question but the safety lanyard will immediately cut the spark when it is pulled out as the switch is then activated. Did you happen to check this? Boats don't normally shut down without any warning...although this switch could do that.

Again, welcome aboard mate.

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[chelanfan]

Thank you Aslan7,

The kill switch will be tested this weekend.

[chelanfan]

I have a bad ECM. Ok we so some are telling me what a pain the thunderbolt ignition is and I should install a ready to run msd distributor and eliminate all that undependable stuff. What does everyone think?

[Bleil05]

I like the Thunderbolt that’s not built into the distributor
A few years Merc put all the electronics in the distributor
They had some problems

Most run the external box an I think they have 4 wires
Pretty durable and seam to last forever

[dustinm]

I would call these guys and have them build a HEI tailored for your app. The last thing you need is a cheap chinese knock-off that will leave you stranded again. I used to believe in GM Performance distrs but unless you can find NOS they too have when china.

https://performancedistributors.com/pro ... tributors/

[chelanfan]

Thank you for the link and your input.

[akorcovelos]

Nothing wrong with Thunderbolt. I’ve had numerous boats with it and never had an issue.

[chelanfan]

Its great until you have to get towed with 7 others in the boat. As i look back I would get a sputtering and pop every so often.

[NWABoater]

Hey Chelanfan, I'm about to embark on a similar project. The previous owner of my boat replaced the Thunderbolt ignition with an MSD setup years ago. I think it worked fine for a while and then started having issues. I looked into the "ready to run" distributors too but after consulting several forums decided to go with a Delco EST kit. Might be overkill.

Here's the kit I purchased. https://www.summitracing.com/parts/rra-18-5514

[chelanfan]

Thanks NWAboater for the link and I did consider that setup. I've decided on this distributor https://performancedistributors.com/pro ... arine-dui/ as I want to support Made in the USA.

There"s one problem I'm having and maybe someone with far more experience can tell me if my 1996 5.7 Mercruiser magnum has a roller cam or a flat top cam? They asked me that when I went to order the distributor and I have no idea.
My serial number is 0F761531 .

[Big Block Power]

A picture of the valve cover will help.

[chelanfan]

If you scroll up there is a picture of the engine. Thank you

[Big Block Power]

If you scroll up there is a picture of the engine. Thank you

Roller. Sorry I don't scroll down that far.
I'm short but not that short!

[chelanfan]

Thanks Big block Power!
Always trying to learn... how can you tell?