mercruiser 5.0 v8 1990 no spark. pls help!

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martyc123

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i viewed a bayliner capri mercruiser 5.0 v8 1990 what was for sale as spares due to not running.it had been standing for 2 years without running.i turned it over and no spark. I then put a live to the coil on the +side and it started and ran great. i towed it home 160 miles and next morning i done the same( live to coil from battery) and now there is no spark.the previous owner said it ran fine 2 years ago when he put it into storage. can some one pls help me. thanks
 
Don S

Don S

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Re: mercruiser 5.0 v8 1990 no spark. pls help!

I would start with this troubleshooting chart.


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04fxdwgi

04fxdwgi

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Re: mercruiser 5.0 v8 1990 no spark. pls help!

Safety lanyard disconnected, maybe? I certainly would start checking from the ignition switch and everything after it.

Try downloading Mercruiser Manual 15, 89-92 GM V8, from the Adults Only section, or other sources, if need be and look at all the diagrams and troubleshooting charts in there.
 
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martyc123

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Re: mercruiser 5.0 v8 1990 no spark. pls help!

many thanks, i will try with that chart in the morning. and post the result. should the safety lanyard wires be joined or un joined for it to run?
 
04fxdwgi

04fxdwgi

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Re: mercruiser 5.0 v8 1990 no spark. pls help!

martyc123 said:
many thanks, i will try with that chart in the morning. and post the result. should the safety lanyard wires be joined or un joined for it to run?
Click to expand...

The circuit needs to be closed, I believe......
 
Don S

Don S

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Re: mercruiser 5.0 v8 1990 no spark. pls help!

i done the same( live to coil from battery) and now there is no spark.
Click to expand...


Since you hot wired the coil, you bypassed the ignition switch, and lanyard safety switch, and you still had no spark. So they are not your problem.
 
04fxdwgi

04fxdwgi

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Re: mercruiser 5.0 v8 1990 no spark. pls help!

Don S said:
Since you hot wired the coil, you bypassed the ignition switch, and lanyard safety switch, and you still had no spark. So they are not your problem.
Click to expand...

I believe he stated "I then put a live to the coil on the +side and it started and ran great " or am I missing something.

That would indicate a problem upstream of the coil, ie: possible problem with ignition switch or safety lanyard.
 
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martyc123

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Re: mercruiser 5.0 v8 1990 no spark. pls help!

iv managed to get it started by unbolting the switch on the gear linkage. i dont know what that switch is for. any ideas, thanks
 
04fxdwgi

04fxdwgi

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Re: mercruiser 5.0 v8 1990 no spark. pls help!

martyc123 said:
iv managed to get it started by unbolting the switch on the gear linkage. i dont know what that switch is for. any ideas, thanks
Click to expand...

Don't understand what the "gear linkage" is. You mean the throttle / shift control? A picture would help immensley.
 
Don S

Don S

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Re: mercruiser 5.0 v8 1990 no spark. pls help!

martyc123 said:
iv managed to get it started by unbolting the switch on the gear linkage. i dont know what that switch is for. any ideas, thanks
Click to expand...

If you are talking about the shift interrupt switch, and it worked when you took it loose, then you probably have a froze up lower shift cable that is keeping your shift interrupt switch activated.
Here is how and why that system exists.
HOW TO: How the Shift Interrupt system works
 
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