1983 Mercury 150hp stator/switchbox

1978 Champion 150hp mercury.

This boat has sat outside for maybe 6 years, I?m trying to get it run right so that my family and I can enjoy it more.

First what I?ve done then the question.

Motor would not run right so I assumed it had to be fuel. Did all kinds of stuff there. Fuel system is good so I moved on to electrical.

Ah ha there?s a miss fire. Cylinders 2&4 will hit sporadically and cylinder #3 is a no show on the timing light. I replaced the wires and cleaned the coils because they were in horrible condition all corroded and such?.retest shows the same problem.

I spray good ol WD 40 into the flywheel while it?s running and wa la it cleared out and seems to be hitting on all six so I go to the lake and first run shows great signs of improvement. I now have good throttle at low speeds, it seems to idle good and I?m so happy. Take the Fam out and guess what? It falls on it?s face again. No low end power, wont idle very well but runs good WOT.

I go home and test with timing light and intermittent spark on 2&4 again with 3 a no show.
Next I pull the flywheel and clean out the trigger, the stator and the flywheel they looked pretty messed up. Put it back together?.same problem.

Now this is what I did next.
According to CDI Electronics web site I did some electrical testing.
I switched the stator leads at the switchboxes and something changed. Left back had spark on all 3 cylinders but no spark on right bank. I put the wires back to there respective places and still no spark at right bank and left bank all hitting fine.

Next I switched the switchboxes. I put the outer to the inner and vice versa. Now I have no spark on the left and I do have spark on the right.

So I replaced the switch boxes with new ones and now I?m hitting on all six?YES.

That?s where I left off. I have not yet test run to see if I have the all clear but I think I?m good.

Here?s the question. Can a bad stator knock out a switch box. Could I possibly have a bad stator? I ask this because of the intermittent misfire that started this whole mess. I really don?t want to buy switchboxes again. So any thoughts?

Re: 1983 Mercury 150hp stator/switchbox

A stator won't hurt a switchbox, but a short in a switchbox will overload and take out a stator.

A bad Bias on the box that was firing will kill spark on the other box, since Merc highly recommends that you change BOTH boxes, you're OK, especially if you used CDI boxes as they are much tougher and if ever a future problem it is OK to change just the one, not both.

Chances are the non-sparking box is good, but there is no bench test to prove it short of bolting it on and checking for spark. It may be worthwhile as you can sell a working box, they are the same one used on the three cyl 75 - 90 HP models.

Re: 1983 Mercury 150hp stator/switchbox

Does your battery charge and tachometer work?

If not, test the rectifier. It's right beside the switchboxes you just changed. Test procedure is in the Engine FAQ on this site.

Re: 1983 Mercury 150hp stator/switchbox

j_martin said:

Does your battery charge and tachometer work?

If not, test the rectifier. It's right beside the switchboxes you just changed. Test procedure is in the Engine FAQ on this site.

Click to expand...

I did replace the rectifier also. That was one of the first things I did when I was going through the fuel and carb issues.

Re: 1983 Mercury 150hp stator/switchbox

Thanks for the input CharlieB. I knew one component could take out another but couldn't remember how it worked. Hopefully I'll get on the water soon and see if the problem is finally solved.

Re: 1983 Mercury 150hp stator/switchbox

easy test for the stator without using special meter can be done with a regular multimeter. make sure there is no continuity(connection) between the charge leads(yellows wires) and the ignition wires that go to switch boxes. my friends boat with merc 150 had a stator that corroded internally and shorted out the ignition side to the charge side of stator. it prob wouldnt hurt to order up a CDI stator(so everything matches) for it. if its the original its probably gonna go bad sooner then later