Arcing problem merc 800

Codedog42

Recruit
Joined
Apr 9, 2011
Messages
1
Recently bought a pontoon with a 1982 merc 800 80 hp and while it runs there is an arc from the boot from the spark plug wire on the coil pack end and it arcs to the closest piece of metal I electric taped it up then it went from the third coil to the fourth well I fixed that now its arcing and I can't see where but I can hear the sound any help I changed spark plug wires and plugs so am I gonna have to get new coils?:facepalm:
 

ONERCBOATER

Chief Petty Officer
Joined
Oct 11, 2010
Messages
536
Re: Arcing problem merc 800

run it in dark with cover off, you'll be able to see it arcing for sure.
arcs are most often insulation issues.

Sean
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Re: Arcing problem merc 800

First remove the spark plugs and wipe off the spot where the plug grounds to the block. Use some straight gas or acetone to make sure the spot is clean. Clean the electrodes o the plugs as well. Install the plugs and clean the porceline body of the plugs as well. if it still arcs, maybe the plug boots are dirty or the plug springs are improperly installed.
 
M

Maxz695

Guest
Re: Arcing problem merc 800

GET NEW WIRES Electrical tape won,t work. the nightime thing is your best bet to find the target. if it,s the coils I have some off a 40 4 stroke may work message me if interested I have 3 of fourView attachment 90270
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: Arcing problem merc 800

After cleaning the tower on the coil, inspect it very carefully in good light.

You may find a thin line burnt into the tower from the arcing, forming a carbon 'trail', lightly sand to remove the carbon or replace the coil.

Replace the boot, it may also have a carbon trail burnt into it.
 
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