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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 15890
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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RE: Mercury 40 HP outboard, 2 cylinder, Serial No. OT518752,

Customer Question

RE: Mercury 40 HP outboard, 2 cylinder, Serial No. OT518752, Model,(###) ###-####d Plugs are not sparking. (Note: the ignition is by key and is mounted on the throttle which is to the right of the steering wheel.)History: After rebuilding the carb and the fuel pump, the motor was starting consistently, and was running full speed in the water (I was impressed!), but, because it was running a little "jerky" at medium and slower speeds, , I decided to change the two plugs. Before removing the old plugs, i tested them without removing them using a plug-in spark indicator (little light bulb that blinks). The tester indicated there was sparking. However, I decided to replace the old plugs anyway using a 0.040 gap (per the SELOC manual).Then, after installing the new plugs, I cannot see any indication of sparking. No sparks can be detected on either cylinder.I did not change anything else on the motor while changing the plugs. (Checked to see if the kill switch is in the up , system on position and found that it is.)Have removed the plugs from the motor and and tried to view any blue sparks when turning on the ignition -- the starter engages and spins the engine, but no sparks can be seen. Also tried the plug tester with the plugs installed -- again, no sparks happen. Also, have tried both the old and new plugs without any sparks on either set.This is really mysterious and frustrating !Questions:1. What are the possible reasons for mysteriously and suddenly losing spark?2. Do you agree that the "jerky" actions sounds like maybe a cylinder was not firing? Other ideas on this ?
Submitted: 9 months ago.
Category: Boat
Expert:  Jason replied 9 months ago.

Hello my name is ***** ***** am I speaking with?

Is the emergency stop switch clip in place?

Customer: replied 9 months ago.
Expert:  Jason replied 9 months ago.

It's typically by the key switch. Is your key switch mounted inside of a remote control, or is it just mounted in the dash?

Customer: replied 9 months ago.
Are you referring to the switch that is sometimes called the dead-man switch ? if so, it is directly below the ignition key. Yes, I checked it. The clip has long been gone, but the switch is in the "up" position.
Expert:  Jason replied 9 months ago.

Yes that's the switch. Those switches do stick so flip it a couple of times up and down and the back up again and let me know if spark returns.

Customer: replied 9 months ago.
ok will go try that now.
Expert:  Jason replied 9 months ago.


Customer: replied 9 months ago.
I flipped the switch up and down a few times and again there is no spark.
Expert:  Jason replied 9 months ago.

The rest of this is going to take a decent quality digital volt/ohm meter to figure out what is wrong. Do you have a quality volt/ohm meter and do you know how to take voltage measurments?

Customer: replied 9 months ago.
do not have one but will get one
Expert:  Jason replied 9 months ago.

You would have to know how to use one, do you know how to use one?

Customer: replied 9 months ago.
i have instructions in the seloc manual for this motor
Expert:  Jason replied 9 months ago.

Okay there are no time limits here, just let me know when you have a meter and we can take it from there.

Customer: replied 9 months ago.
ok thanks
Expert:  Jason replied 9 months ago.

Sure thing.

Customer: replied 9 months ago.
get back with you when i know more. tks and out
Expert:  Jason replied 9 months ago.

Correct, just post back here when you are ready.

Expert:  Jason replied 8 months ago.

How did you end up making out?

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