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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3343
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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40hp 2 stroke Mercury. New fuel, turning over ok, spark

Customer Question

40hp 2 stroke Mercury. New fuel, turning over ok, spark plugs new and wet,
JA: Sometimes things that you think will be really complicated end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so the Marine Mechanic can help you best.
Customer: 40 HP Merc 2 stroke. Fresh fuel, turning ok, spark plugs new and wet,
JA: Is there anything else the Marine Mechanic should be aware of?
Customer: Cutoff switch up
Submitted: 2 months ago.
Category: Boat
Expert:  Charles replied 2 months ago.

Hello, my name is***** will assist you.

Expert:  Charles replied 2 months ago.

Would you please post the serial number of the engine?

Has the engine been sitting for some time?

Have you tested it for spark?

Customer: replied 2 months ago.
OT925829 sorry had to go to engine
Yes been sitting for some time
Tested for spark No
Customer: replied 2 months ago.
Thot maybe coil but where to find it.
How to test for spark?
Expert:  Charles replied 2 months ago.

Ok, got it.

First you are going to need to test and see if you are getting spark. This can be done with an adjustable gap spark tester that can be rented from most chain auto parts stores.

Customer: replied 2 months ago.
Engine turns over but never fires. I suspect ignition. How to test?
Expert:  Charles replied 2 months ago.

Do you have a good quality digital multimeter?

Customer: replied 2 months ago.
Do I pull a plug out then turn engine over to see a spark.
No multimeter
Expert:  Charles replied 2 months ago.

That is not the proper way, but is can be done that way. Use a pair of insulated pliers to hold the wire, and have a helper crank the engine over while you are holding the plug neat the block. See if there is any spark on it.

Customer: replied 2 months ago.
Im about to tempt right now
Customer: replied 2 months ago.
Im on my own but pulled a pug and can't see any spark
Customer: replied 2 months ago.
No spark. Could the cutoff switch be faulty
Customer: replied 2 months ago.
Im on my computer in the house and the boat is in the driveway. I have to run baCK n forth.
Expert:  Charles replied 2 months ago.

Sorry for the delay, I had to step away from the computer for a bit.

On the kill switch, unplug the black/yellow wire and try the test for spark again. It is really best if you can be right there at the plug to watch it.

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