I have a pair of older 1989 135 mercs, I think they run good, crank up easy, idle good and are realy strong at 125lbs in every hole. A mechanic in columbia was doing some wiring on something else on the boat and had to run it. He later says that port motor is not running on all cylinders as just an FYI for me. I get home and put the hose to it and it seems to run just fine and on the lake also. So, I start getting paranoid and thinking that maybe it should run better. I crank it and pull a few plug wires off and when I pull a couple of plug wires (only did one at a time), it does not effect the engine at all. Some made a drastic diference but a couple (all on left bank) did not effect it. Here is what is puzzling me, I can see a nice blue spark on every plug wire. My questions are, if I have fire to every plug, then can my power pack (switchbox) still be bad? Can it be running as good as it does on 4 cylinders? Should a wire pulled off always have a noticeable effect? The motors only turn about 4800 rpm at WOT with 19P stainless props but that is 41mph on the boat.
Rick
This was off another site…
Hey G. I had a similar prob with my '86 Merc 150. ODDD1 helped me out pointing me to the stator(see my april 14th post). All of the sudden one day she started to run sluggish and wouldn’t go anywhere. I found weak spark on cyl 1, 3 & 5, but strong on 2, 4 & 6. When i pulled the wires off of 1,3 & 5, no change, but they would spark while out of he motor. Guess it wasn’t strong enough to fire under pressure in the cylinder. The windings in the stator went bad. i repalced the stator ($150) as per ODDD1 and she runs perfect now. Not sure if this info will help in your situation with a different motor, but figured i’d pass it along. Good luck.
I would pull 2 plugs at a time to eliminate the spark boxes… Should have a spark box per 2 cylinder, assuming it is a 4 banger.
2502 trophy twin 175 mercs
“The Rum Runner”
For sale… $12.5k Get offshore cheap!!!
That is exactly what my symptoms are, weak spark on 1-3-5 but I have two power packs, one does 1-3-5 and the other does 2-4-6
How do I determine if my problem is switch boxes (P Packs) or stator?
Rick
swap the switch boxes and see if it follows the box
I’m now at www.teamcharlestonmarine.com
■■■■, I should have thought of that 
Chris,
If the weak spark does change banks when I swap boxes, can I get away with just buying one. I have always heard you need to change both whenever one has issues?
Thanks
Rick
I had to change one of mine a couple months ago. I could pull all three plugs on one side and the motor would run the exact same… but was still getting spark on that side when i had the plug out.
I bought 2 off a used blown motor and still have one of them left. If you are around Myrtle you are welcome to it.
I have no idea if it is the same??? It fits fine on a 1993 175 Merc.
If your motor is a 4 cylinder, i doubt it will.
2502 trophy twin 175 mercs
“The Rum Runner”
For sale… $12.5k Get offshore cheap!!!
Coates2122,
I have a 6 cylinder. Did the Power Pack you replaced fix your problem?
My switch box part number is 114-7778 and I work in Myrtle beach often and may be down there toward the end of this week. How much do you want for it? I’d like to try it if they are interchangeable and I will check part numbers to see.
Thanks
Rick
Coates2122,
You have a PM
I won’t be back in town till the 28th. Heading down to Daytona tomorrow to try and catch some fish down there.
You can have it. Just been sitting around in my cabin in case i need it. Might actually have a extra stator you can try.
It did fix my problem.
2502 trophy twin 175 mercs
“The Rum Runner”
For sale… $12.5k Get offshore cheap!!!