Hi speed missing, Force 70, 1995

[jakutija]

The engine can not be more than 3200 rpm. Measured with the DVA to red stator adapter, between the blue wire and gnd, the voltage goes up 900V, never measured directly on the stator.
P.S. does what red adapter???

 

[pnwboat]

First disconnect the two yellow wires from the stator to the voltage regulator. If that corrects the problem, replace the voltage regulator.

If disconnecting the voltage regulator has no affect, then disconnect the Blue stator wire from the Switch Box and read from the Blue stator wire to ground (engine block). It should be 3250 - 3650 Ohms. Do the same thing with the Red stator wire. It should read 75 - 90 Ohms. The stator on your motor has a high speed winding (Red stator wire) and a low speed winding (Blue stator wire). Sounds like there is a possibility that the high speed winding could be bad.

 

[jakutija]

Thank you for your help!
My stator has two yellow wires and the two green / white. yellow go to the rectifier a green / white on the adapter. I do not have the red wire from the stator. I timed voltage with blue wire adapter, go to 900V at high RPM, whether it can be a problem. Somewhere I saw that it does not need over 400V.

 

[jerryjerry05]

You need a special "peak reading volt meter" to measure voltage from the stator..
A regular meter will NOT work.
​The OHMS between the 2 green :green/white and white green should be about 700ohms.
And 180V measured with a peak reading meter.
Unless the stator is a CDI stator and the reading could be lower.
CDI or Outboard Ignition dot Com both have test procedures and test values for your motor.
I believe your electronics are all Mercury.

Even then the stator coud be bad if the voltage isn't enough.

I'm working on a Mercury 50 hp.
The stators ohms read right at 700 the DVA voltage is 45v not the 180 it needs.

But if you can get up to 3500 I wouldn't bet the stator is bad???

Do a compression test.
Pull the carbs and check the reeds. A miss at high speeds could be damaged reeds???

 

[pnwboat]

A couple of things to check before focusing too much on the ignition system. Is the engine hard to start, or does it start good after one or two attempts?

Check compression. You should not see more than 10% difference from the highest to lowest reading.

Carburetors. Make sure the carburetors are clean inside and no debris in the fuel bowls.

Fuel pump. Make sure the diaphragm is not hard and stiff. Should be relatively soft and flexible.

Sounds like you have the ignition system that the manufacturer was using in transitioning from the Switch Box type system to the CDM type. Stators that have the Green/White and White/Green wires should read 500 - 700 Ohms with the wires disconnected from the harness.

You should have a Switch Box that drives the ignition coils? The adapter in line with the stator conditions the voltage going to the Switch Box either by smoothing out spikes and or reducing the voltage, not exactly sure what it does.

How are you measuring the voltage? Are you using a DVA adapter on your meter? If you are, the meter should be set to DC volts and measured on the Green/White and White/Green stator wires. Typically you should see around 180 to 200 volts DC with the engine running.

1. Measure the resistance across the Green/White and White/Green stator wires. Should see 500 - 700 Ohms. Make sure the wires are disconnected from the harness.
2. Check the voltage regulator output. You should see 13.5 to 14.5 volts DC on the red wire at a minimum of 2500 RPMs. Also try disconnecting the two yellow wires that go from the stator to the regulator to see if that has any affect on the problem.