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  Mercury 7.5Hp Outboard. No spark.

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Author Topic:   Mercury 7.5Hp Outboard. No spark.
pepperpot posted 04-30-2008 04:08 AM ET (US)   Profile for pepperpot   Send Email to pepperpot  
Guess I need some helping out here.
Yesterday I brought home my very first out board engine.
Not new but looking ok clean and neat.

I guess its app 15 years old but seems to have been running only a few hours.

But no spark from none of the two spark plugs.

Tried out:

Two new spark plugs.

Cleaning the spark plug wires at both ends.
Widened the upper end of spark plug wires in order to get better connection.
To eliminate the possibility of a short cut in a switch I removed the black wire from the stopswitch from engine.

Still no spark.

What could possibly be wrong here ?



pepperpot posted 04-30-2008 04:39 AM ET (US)     Profile for pepperpot  Send Email to pepperpot     
Hey again.

I just uploaded 3 pictures of the engine to


jimh posted 04-30-2008 09:29 AM ET (US)     Profile for jimh  Send Email to jimh     
The most common cause of no spark is the absence of the safety lanyard in the safety lanyard switch. Without it in place, there will be no spark.
pepperpot posted 05-01-2008 08:09 AM ET (US)     Profile for pepperpot  Send Email to pepperpot     
Thanks J

Since the two wires for the safety lanyard switch are the tvo orange wires from the box 2 in my photos
( )
it would probably be ok to cross circuit those with a piece of wire directly at the box ?
(For the test only of course !!)
Or would that ruin anything hidden in the box or elsewhere ?


jimh posted 05-01-2008 10:48 AM ET (US)     Profile for jimh  Send Email to jimh     
On my motor, the safety circuit is CLOSED to suppress ignition. I do not know how it works on your motor. If may work in the opposite sense.
pepperpot posted 05-01-2008 10:30 PM ET (US)     Profile for pepperpot  Send Email to pepperpot     
Thanks Jimh

Yesterday I found an old local guy who practically breathes through these old Mercury engines.
He has promissed to help me out here. He has several scrap engines for spare parts and says that my engine will be up and running in a day ... Let´s se that ...

I will for sure be back and check this site from time to time.

Many thanks here from Denmark


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