1985 Mercury 115 Hp only 3 cylinders firing

[firefighter2112]

I have a 1985 Mercury 115 inline 6, after doing a spark test i found i only have 3 cylinders firing 1,3,5.cylinders 2,4,6 are the ones that are not working,what kind of problems am i having i dont belive its the coils im thinking somthing between the stator,trigger plate or switch box's,Can someone help me out and explain how to test each componet so im not thowing parts at a problem.Thanks..

 

[Laddies]

Re: 1985 Mercury 115 Hp only 3 cylinders firing

Either have a bad switchbox or stator, to tell which is bad swap the red and red white wires and the blue and the blue white wire on the boxes, if the spark changes cyls it's a bad stator if it stays on the same cyls it's the box.

 

[CharlieB]

Re: 1985 Mercury 115 Hp only 3 cylinders firing

Second test, disconnect the White wire on the Bias terminal of both switchboxes, retest for spark.

If you now have spark on all six, the original sparking switchbox has a Bad Bias circuit, blocking the spark from the other switchbox.

Factory recommends replacing BOTH switchboxes.

Both boxes will work perfectly fine on a three cyl motor 75 - 90 HP.

 

[firefighter2112]

Re: 1985 Mercury 115 Hp only 3 cylinders firing

Ok I did swap the wires from the stator going into the switchboxs I still only have fire on 1,3,5 so I got a new switchbox and installed it and I still don't have fire on 2,4,6. Could the box that controls 1,3,5 be bad but still work 1,3,5.is this a bad bias circuit in the 1,3,5 box not allowing 246 box to function?

 

[Laddies]

Re: 1985 Mercury 115 Hp only 3 cylinders firing

Sounds like a bad bias it the other box, remove the bias wire between the 2 boxes as Charlie describes in his post

 

[firefighter2112]

Re: 1985 Mercury 115 Hp only 3 cylinders firing

Well come to find out I goof up badly,what I thought was the stator wires turn out to be the trigger plate wires and by doingt his I believe I had a bad switchbox, I I know it's the stator because I switch the stator wires and now 2,4,6 is working and 1,3,5 are not.so now I have a extra switchbox and I also need a stator.

 

[17rogue70]

Re: 1985 Mercury 115 Hp only 3 cylinders firing

would this also be true on a 1986 xr2 150 ? i have no fire on #1#3#5 cylinders.

 

[Laddies]

Re: 1985 Mercury 115 Hp only 3 cylinders firing

Yes

 

[CharlieB]

Re: 1985 Mercury 115 Hp only 3 cylinders firing

would this also be true on a 1986 xr2 150 ? i have no fire on #1#3#5 cylinders.

Please start your own thread so we can help you sort out your problem, it could be either a stator or that sparking switchbox has a bad Bias circuit blocking the other box from firing. Disconnect the White Bias wire linking the two boxes, if spark returns to all cyls then the original sparking box is bad.