Mercruiser 4.3 Ignition Troubleshoot Process

Viliant25

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Jun 2, 2022
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Hi, I have a MCM 4.3 Litre Mercruiser, Thunderbolt Ignition engine. Engine failed to start after the kill switch was deployed while running. I returned the switch to the run position. It will crank, it appears to be getting fuel. Will not start. Serial no is L355976. Is there a procedure/process available to follow to trouble shoot the ignition firing system? Thank you.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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It's in the stickies at the top of the forum
 

achris

More fish than mountain goat
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27,468
Ues a test light and check for power on the coil+. I suspect you hacve a kill switch problem, but that test will confirm.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Thank you...not sure what stickies are, new to the forum, but I'll try to find that.
at the top of the forums are threads that are stuck and the icon looks like a sticky note or post it note. the one that says mercruiser information. open that. in there is all the stuff you need for troubleshooting mercruiser stuff. every forum has at least one sticky.
 

Jonatande

Seaman Apprentice
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May 19, 2022
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To you get the Audio warning signal system when you push key to "RUN"?
 

Viliant25

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Jun 2, 2022
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Thank you...not sure what stickies are, new to the forum, but I'll try to find that.
Just an update. I did follow the purple wires from the kill switch. Found a connection that went to the dashboard controls that appeared very loose. I remade the connection securely…and the engine fired up! Second weekend out and all is good! Thank you for the suggestion and to all other members that helped me to trouble shoot this issue. Very much appreciated!
 

dubs283

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Jul 27, 2005
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5,343
Thank you for the suggestion and to all other members that helped me to trouble shoot this issue. Very much appreciated!
Glad you're set and figured out, enjoy

For posterity, did you read and follow the suggested stickies at top of forum page?
 

Bondo

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Yes. I see how to navigate through them now. S/O to Scott!
Ayuh,.... Welcome Aboard,.... They are also available through the link in my signature titled Don's Adults Only Section,.....
 
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