2000 Johnson 90 V4 60 degree carbureted: no spark on all 4 cylinders

[Mischief Managed]

Tested the charge coil, power coil (I do happen to have a Fluke 87 DVM that'll measure the peak voltage correctly) and they passed both voltage and impedance. Verified it's not the stop circuit. Inspected/cleaned the optical bits and they look fine. Battery connections are tight.

The only thing that seems off is the voltage at the yellow/red wire while cranking. I've read that it needs to be more than 11 volts and I only see 8.5 volts. Engine cranks nice and fast though. Planning to try a different battery tomorrow and if that does not change the voltage, will check the starter solenoid for excessive resistance with a bypass.

Assuming the battery and solenoid check does not help:

I don't really want to throw parts at it but it seems like it's either the optical pickup or the ignition module. Any ideas?

 

[boobie]

Re: 2000 Johnson 90 V4 60 degree carbureted: no spark on all 4 cylinders

As long as the voltages are good all around the pack/osi senser, I'd go for a pack or sensor.

 

[clanton]

Re: 2000 Johnson 90 V4 60 degree carbureted: no spark on all 4 cylinders

I have a Fluke 87, mine will not do peak volts without an adapter.
You sould see 150 peak volts from the stator side, and 100 peak volts at the primary side of the coil. 35 peak volts from the power coil.

 

[Mischief Managed]

Re: 2000 Johnson 90 V4 60 degree carbureted: no spark on all 4 cylinders

I have a Fluke 87, mine will not do peak volts without an adapter.
You sould see 150 peak volts from the stator side, and 100 peak volts at the primary side of the coil. 35 peak volts from the power coil.

When you are in record MAX mode, press the button that normally turns on the beep for continuity. That changes the read time for max record from 100ms to 1ms. To prove it works, plug it into a 120VAC outlet and you'll see around 170 volts.

 

[clanton]

Re: 2000 Johnson 90 V4 60 degree carbureted: no spark on all 4 cylinders

Will try this tomorrow afternoon.

 

[Mischief Managed]

Re: 2000 Johnson 90 V4 60 degree carbureted: no spark on all 4 cylinders

Update: Got ahold of an oscilloscope and tested the optical sensor. It tested fine so the only possible problem was the ignition module itself. Put a new igntion module in it and it fired right up. That was an interesting project, I'd never worked on an outboard before. It has a lot of clever design elements.

 

[petryshyn]

Re: 2000 Johnson 90 V4 60 degree carbureted: no spark on all 4 cylinders

When you are in record MAX mode, press the button that normally turns on the beep for continuity. That changes the read time for max record from 100ms to 1ms. To prove it works, plug it into a 120VAC outlet and you'll see around 170 volts.

This will only register the highest voltage which occurs, it doesn't give live readings. If you were lucky enough to get one good pulse, it would register that peak voltage. A DVA adapter still gives better readings, as it is almost "live".

Good on you for fixing it!!!

 

[Mischief Managed]

Re: 2000 Johnson 90 V4 60 degree carbureted: no spark on all 4 cylinders

Every description of DVA that I have read says "peak voltage". My Fluke 87 can resolve voltage peaks down to 1 millisecond in duration and stores the highest reading it has taken in these 1 millisecond time slots. When the engine is cranking at 250-350 RPM the duration of the wave forms from the charge and power coils is long enough that the peak voltage can easily be resolved within those 1 millisecond time slots.

I'm not sure how many magnets there are on the flywheel, but if there's 4 of them, and the engine is turning at 350 RPM while cranking, the Fluke 87 is able to resolve 43 distinct measurements per wave and there's 23 waves per second of cranking. Fewer magnets and or a lower cranking speed give the meter even more opportunites to catch the peak voltage.

Anyway, the measurements I made were within spec and ruled out the charge and power coils. As it turns out, there was nothing wrong with the charge and power coils and the engine is running fine with a new ignition module from CDI.

 

[petryshyn]

Re: 2000 Johnson 90 V4 60 degree carbureted: no spark on all 4 cylinders

The min/max mode displays and holds the highest reading achieved. One good pulse in a series of poor pulses will display the good pulse only. The DVA function will display poor pulses more accurately.....

When you do run into a flakey stator, you will appreciate the difference!! trust me