merc 850/ no spark on 3 & 4

[mgross]

80 hp 4cyl, around 1980 vintage by serial number.

I've replaced the wires from the electronic box to the coils, and swapped around the coils and HT wires to establish that the wires and coils work ok. That would seem to leave the black box, the stator, or the trigger assembly as suspect. How would I determine which or what part is not functioning? Clymer manual says check ohms across trigger leads, and that tests OK.

Any suggestions, short of R&R?

thanks,
Mark

 

[Laddies]

Re: merc 850/ no spark on 3 & 4

Swap the blue and blue white wires and the red red white wires on the box and see if the failure moves or goes with the wires

 

[mgross]

Re: merc 850/ no spark on 3 & 4

Swap the blue and blue white wires and the red red white wires on the box and see if the failure moves or goes with the wires

I don't see these colors, the wire colors are rather faded...
Do you mean the wires from the stator, trigger, or to the coils?

thanks!

 

[Laddies]

Re: merc 850/ no spark on 3 & 4

Stator

 

[mgross]

Re: merc 850/ no spark on 3 & 4

I swapped the leads, had spark on 1, 2, 3, no 4.
put leads back, I have spark on all cylinders!

what do you suppose that means?

 

[ricksrster]

Re: merc 850/ no spark on 3 & 4

Bad connection originally. There might have been a little corrosion that got cleaned away when you were switching wires. you may have bad insulaion somewhere also. Check your wires real good.

 

[Laddies]

Re: merc 850/ no spark on 3 & 4

Hope it was a connection like rick says the other option is expencive 8)

 

[mgross]

Re: merc 850/ no spark on 3 & 4

when testing plugs, the plug wires arc to motor (when no plug present) with a nice bright spark. Is this a sign to replace the plug wires as well? There are two sets of four wires bundled from the switch box to the coils; are these available still? motor is a '79.

Motor ran excellently, and about the time I congratulated myself on getting it going, I ran out of gas! Made new friends with a family on a pontoon boat who towed me in... Guess relacing the defective gas guage is next!

I put 6 gallons of gas in it two weeks ago, and last night it only ran for about an hour before going dry. Never had a boat before, but that seems like excessive consumption, or I'm loosing it somewhere (leakage, evaporation?)