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70 hp mercury 1989 no fire

B

Big Al

New member
Won't start 1989. 70 hp. Merc

No fire at spark plugs. Moter cranks forever won't start. I was told that the mercury switch would cause this. I looked in the diagram and it goes from the harness plug to the switchbox, I don't know what it really does,must close the circuit some how. Could somebody tell me where to find it on the moter and how to test it? If that isn't the prob. what else could I check. Thanks
 
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the stator and triger go to the switch box i think the best way to go is to pay the shop halh hour to diagnosis the problem or u can spend 40 on a manual horse a piece easy to replace that stuff urself once u figure out the problem
 
If you look on the switchbox, along the bottom (front) there are 4 little screw terminals.

The third from the left should have two wires, black with yellow stripe, connected.

One goes to the harness the second goes to the mercury switch.

When either the mercury switch says the motor is tilted or you turn the key off (or the safety lanyard is pulled, if equipped) the ignition gets grounded out.

So find those blk/yellow wires and follow them - unhook the one for the mercury switch and try to start.

If it's still a "no go", disconnect the other blk/yel wire that goes to the harness. If it starts then you have either a problem in the harness or a bad keyswitch.

If it does start with both those wires disconnected you will have no way to "shut down" the motor, so you either have to choke it out or pull the fuel line and let it run out of gas...
 
;)that was well said

galamb said:
If you look on the switchbox, along the bottom (front) there are 4 little screw terminals.

The third from the left should have two wires, black with yellow stripe, connected.

One goes to the harness the second goes to the mercury switch.

When either the mercury switch says the motor is tilted or you turn the key off (or the safety lanyard is pulled, if equipped) the ignition gets grounded out.

So find those blk/yellow wires and follow them - unhook the one for the mercury switch and try to start.

If it's still a "no go", disconnect the other blk/yel wire that goes to the harness. If it starts then you have either a problem in the harness or a bad keyswitch.

If it does start with both those wires disconnected you will have no way to "shut down" the motor, so you either have to choke it out or pull the fuel line and let it run out of gas...
Click to expand...
 
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