zaschf
Member
Hello all,
here is a really difficult on, I guess.
I got this motor earlier this year when I bought a classic boat that needed some TLC.
The motor is a 80hp 4 cylinder 2 stroke Mercury from about 1980 of which the wiring was in a pretty poor state. (wire rot) I have replaced the wire harness.
Anyway, when I got the motor 1-2 fired okay, 3-4 didn't fire. (no spark)
Checked the trigger module and found a nearly broken wire, which I replaced with no change for the problem.
Swapped 1-2 with 3-4 trigger wires. 1-2 still fired okay, 3-4 still not firing.
Trigger module must be okay.
Swapped the stator wires (red/redwhite) (blue/bluewhite). 1-2 still fired okay, 3-4 still not firing.
Stator must be okay.
Swapped 1-2 with 3-4 coil wires. 1-2 stopped firing and 3-4 came right.
Coils okay.
There is only one thing left and that's the switch box.
Bought a new switch box, wired everything up.
Now here is my new problem that completely mystifies me.
I've marked the flywheel with all cylinder's TDC so I can verify that each cylinder gets a spark at the right time.
Strobe from No1 shows on No2 TDC mark
Strobe from No2 shows on No2 TDC mark
Strobe from No3 shows on No3 TDC mark
Strobe from No4 shows on No4 TDC mark
Well, the sparks are just before TDC of course.
Disconnecting No2 coil wire from the switch box makes No1 fire at the correct timing.
As I'm writing this up I realise that I've been prodding and pulling on just about all wires and maybe I have a short to the coils between 1 and 2. (edited)
I'll check that tomorrow morning because now is beer'a'clock
Anyway, anyone got any idea where to start with this problem.
here is a really difficult on, I guess.
I got this motor earlier this year when I bought a classic boat that needed some TLC.
The motor is a 80hp 4 cylinder 2 stroke Mercury from about 1980 of which the wiring was in a pretty poor state. (wire rot) I have replaced the wire harness.
Anyway, when I got the motor 1-2 fired okay, 3-4 didn't fire. (no spark)
Checked the trigger module and found a nearly broken wire, which I replaced with no change for the problem.
Swapped 1-2 with 3-4 trigger wires. 1-2 still fired okay, 3-4 still not firing.
Trigger module must be okay.
Swapped the stator wires (red/redwhite) (blue/bluewhite). 1-2 still fired okay, 3-4 still not firing.
Stator must be okay.
Swapped 1-2 with 3-4 coil wires. 1-2 stopped firing and 3-4 came right.
Coils okay.
There is only one thing left and that's the switch box.
Bought a new switch box, wired everything up.
Now here is my new problem that completely mystifies me.
I've marked the flywheel with all cylinder's TDC so I can verify that each cylinder gets a spark at the right time.
Strobe from No1 shows on No2 TDC mark
Strobe from No2 shows on No2 TDC mark
Strobe from No3 shows on No3 TDC mark
Strobe from No4 shows on No4 TDC mark
Well, the sparks are just before TDC of course.
Disconnecting No2 coil wire from the switch box makes No1 fire at the correct timing.
As I'm writing this up I realise that I've been prodding and pulling on just about all wires and maybe I have a short to the coils between 1 and 2. (edited)
I'll check that tomorrow morning because now is beer'a'clock
Anyway, anyone got any idea where to start with this problem.
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