1979 Mercury 40HP - Ignition Switch Box, Replacing wires...

[TheChad]

Re: 1979 Mercury 40HP - Ignition Switch Box, Replacing wires...

I installed the new SIerra Brand Switch Box, Which is a rebuilt OEM Switch Box (Has Mercury's name on it)<br /><br />Still no spark, Again i took off the orange wire, and got spark.<br /><br />So I guess the switch box wasn't the problem. <br /><br />So what IS the problem?<br /><br />Thanks,<br /><br />-TheChad

 

[Laddies]

Re: 1979 Mercury 40HP - Ignition Switch Box, Replacing wires...

If you have spark with the orange wire off then you have a wire in the harness shorted or a bad ign. switch ck the cicruit with your ohm meter, with the switch on the cicurt should be open and closed with it off, did you disconnect the mercury switch and see if it was shorted?

 

[TheChad]

Re: 1979 Mercury 40HP - Ignition Switch Box, Replacing wires...

Well I found one of the wires from a different wireharness was not making good contact, and had already been fixed with a butt coupler... I cut the coupler off, and installed a new one.<br /><br />Now The spark works, and the engine fires...<br /><br />... BUT now the impeller shreaded.. I JUST replaced the water pump less than a month ago, so I don't understand why..<br /><br />Obviously I havent even had the boat on the water.. I've only ran it maybe a total of 10 minutes...<br /><br />Does running the engine with out water, only for a short time (20-30 seconds), cause the impeller to shread?<br /><br /><br />Thanks again,<br /><br />-TheChad

 

[Motor Boater Bill]

Re: 1979 Mercury 40HP - Ignition Switch Box, Replacing wires...

I've heard it said that, yes, running it for even a very short time out of the water can trash the impeller. This might be especially true with a brand new impeller, that isn't "broken in" although I can't testiy to this from my own experience.

 

[kam80500]

Ignition Switch not shutting engine off

Ignition Switch not shutting engine off

I installed a new console on my --1984 Sun tracker party barge. Now the ignition switch will not kill the engine. The engine is 1986 50HP Mercury. I've attached some pictures of the switch if anyone could help or tell me what each wire goes to.

 

[Pekka]

Re: 1979 Mercury 40HP - Ignition Switch Box, Replacing wires...

Well... if it's the same as my 60hp merc.....

The switch box has 10 connection in total.
4 in a row on top, and 6 in two coloums below.
The left most connection, of the top four, is the one from the stator.
The next connection has a black/yellow wire. This is the stop signal. Disconnect this wire and check the ohm value between this wire and ground.
With the key in off pos. -> zero ohm (full connection)
With the key in on pos. -> no ohm (no connection)

Look at sketch attached.
This is a simplified diagram.