1975 Evinrude 75HP Hustler No Spark Problems

1975 Evinrude 75HP Hustler
The motor always sounded like it wanted to start but wouldn't because it was getting no spark. We found that our power pack was bad and replaced it. We took the it out on the river last night and it ran great and got up and drove great. We took it out today seemed to be running fine then after about half an hour it just shut off. We couldn't get it started again, then the battery went dead. We got towed back in and brought it home and charged the battery. Now it sounds like before we replaced the power pack. Could it have gone bad already or is there something we are missing that would make the power pack go bad again.

We were told to check the black/yellow wire from the power pack and I disconnected the Black/Yellow wire at the power pack. I have a DC Voltage meter and set it to the lowest DC Voltage reading. I put one end on the black yellow wire and the other to the ground wire right below the power pack but I am not getting any readings at all.

I tried with the ignition key in the OFF position, and got no reading. Then I turned the ignition key to the ON position and got no reading there either.
I also had issues with the battery going dead so I was told to check the rectifier. I removed the rectifier wires from the terminal block and used a ohm meter, connected the black lead of the ohm meter to the rectifier base (ground), then one by one, I connected the red lead of the ohm meter to the yellow reading was 0 or 250 DC, yellow/gray reading was 0 or 250 DC, and the red wire reading 3 or 160 DC. I ran it under the OHM part but didn't know how to read it exactly thats why I included the DC readings number.

Then I reversed the ohm meter leads and checked those same wires again and got no readings.
I then connected the black lead of the ohm meter tothe red wire from the rectifier and the red lead to yellow reading 0 or 250 DC, yellow/gray reading was 0 or 250 DC.
I then connected the red lead of the ohm meter to the red wire from the rectifier and the black lead to yellow reading 1K or 10 DC, yellow/gray reading was 1K or 10 DC.

What does this information give me. Does it mean I need to replace the power pack again and the rectifier.

What would cause this power pack to go bad a second time since we already replaced it Friday?

The stator looks good no burns and none of the coating and so does the wires coming off of it.

Re: 1975 Evinrude 75HP Hustler No Spark Problems

welcome to iboats!

The black/yellow wire is your kill circuit - the keyswitch connects this wire to ground when the key is off, shorting the ignition to ground which prevents it from generating the spark. To check it, you would need to disconnect it and do a spark test.

But I don't think you have to do that - the dead battery is a clue pointing to faulty rectifier, which you confirmed with the 2nd part of your test (red wire).

Rectifiers sometimes (but not always) fail in a way that grounds out the ignition. Disconnect all the rectifier leads and try again - if she starts, or if you get spark, a new rectifier is all you need. Running the engine without a rectifier won't hurt it - it just won't charge the battery.

Some things that damage rectifiers: running the engine without a battery, or with a loose or corroded battery cable, or reversing the battery cables.

Post your results.

Re: 1975 Evinrude 75HP Hustler No Spark Problems

We removed the rectifier and the motor still would not start and we charged the battery off the boat on a charger all night and took it and had it checked and the battery tested good. We also did a OHM reading on the stator wires (disconnecting the yellow and yellow/gray wires from the stator, we hooked one lead to the yellow and one to the yellow gray and got readings, then we hooked one lead to the ground and one to each of the yellow wires and got readings on either) those checked out good according to the test I was given to check it.

I am at a complete loss. I hate to replace the power pack again just to have it fail again like the one we put in on Friday. Is there an actual test to run to see if the power pack is actually bad? What else could make a power pack go bad. I don't know what a neon tester is or I would check the timer base and sensor assembly. Could that be the problem and is there a way to test those with a DC Voltage Meter or an OHM Meter?

Any help would be greatly appreciated and the help we have already gotten is also greatly appreciated.

Thank you and have a good day.

Re: 1975 Evinrude 75HP Hustler No Spark Problems

NO SPARK ON ANY CYLINDER:
(Note: If the engine has spark with the spark plugs out but not with them installed, the timer base is either weak or the engine is not spinning fast enough. See # 6 and #8.)
1. Disconnect the black yellow stop wire and retest. If the engines' ignition now has spark, the stop circuit has a fault-possibly the key switch, harness or shift switch.
2. Disconnect the yellow wires from the rectifier and retest. If the engine has spark, replace the rectifier.
3. Check the stator resistance. You should read about 500 ohms from the brown wire to the brown/yellow wire.
4. Check the DVA output from the stator. You should have a reading of at least 150V or more from the brown wire to the brown/yellow wire (while connected to the pack).
5. Check the timer base resistance from the #1 to the #3 sensor wire, and from the #2 to the #4 sensor wire. Reading should be 10-20 ohms on each set (or 30-40 ohms for CDI Electronics Blue Timer Bases).
6. Check the DVA output from the timer base. A reading of at least 0.5V or more from the #1 sensor wire to the #3 sensor wire, and from the #2 sensor wire to the #4 sensor wire (while connected to the pack) is needed to fire the pack. If the output is low, you may try to reset the air gap between the timer base sensor and the triggering magnet using a Sensor Gap Gauge (553-9702) or use the following procedure:
a) Loosen the two mounting screws on the sensors and the nuts located in the epoxy on the outside of the heat shield of the timer base.
b) Slide the sensors in toward the crankshaft until the sensor touches the stop boss located at the base of the sensor mounting area. Tighten the mounting screws.
c) Coat the face of the sensors with machinists bluing or equivalent.
d) Install the flywheel without the key and rotate the flywheel at least one full turn.
e) Remove the flywheel and check to see if the trigging magnet struck the face of the sensors. If it did, back the sensor out approximately 0.005? and repeat steps c, d and e.
f) If the ignition fired, finger tight the nuts on the outside of the heat shield and coat them with RTV.
g) If still no fire, replace the sensor.
7. Check the DVA voltage on each black/white wire to engine ground. You should have a reading of at least 150V or more (while connected to the pack). If the reading is low, disconnect the trigger wires from the pack and recheck the black/white terminals on the pack. If the voltage jumps up to an acceptable reading, the timer base may have a problem in the internal wiring (possibly a thin spot in the insulation on one wire).
8. Check the cranking RPM. A cranking speed of less than 250-RPM will not allow the system to fire properly.

Re: 1975 Evinrude 75HP Hustler No Spark Problems

Check the DVA output on the orange wires from the power pack while connected to the ignition coils. You should have a reading of at least 150V or more. If the reading is low on one cylinder, disconnect the orange wire from the ignition coil for that cylinder and reconnect it to a load resistor. Retest. If the reading is good, the ignition coil is likely bad. A continued low reading indicates a bad power pack.