Trouble Shooting 1993 70HP Johnson OB

[Rick D]

This engine is on a shared pontoon boat. Fresh water. In the last year we has problems on start-up but ran fine once warmerd up. Then we had two sets of problems with people not being able to restart despite the engine spinning well and using starting fluid. So, I went to the boat today and these are my notes. How do you check an electronic ignition module? Any suggestions welcome!

Hot on the track of engine probs: 1993 Johnson 70 HP two cycle.

Checked compression, All 90+.

Checked spark plugs. Good. Not burnt nor wet.
checked wires around engine. A few were loose but connected.

Checked fuses on the engine. All OK.

Checked fuel filter, Pumps good fuel though filter.

Pulled air cleaner. Drained all carbs. Fuel looked and smelled good. Pulled all fuel lines. Sprayed carb cleaner in all intake and bowl fittings. All passages appeared clean. Boat gets plenty of fresh fuel.

Checked for spark. None detected. Tried grounding spark plugs. No spark detected. Check using a (suspect) in-line tester. No spark.

Pulled ignition switch. Tested connectors and "dead man's switch". Installed back-up ignition switch. No difference in action or voltages.
Reinstalled original switch.

Suspect after all this that the problem may lie in the electronic ignition module.

Next step is to find a manual and an on-line forum.

 

[Stu Jackson]

Rick,

I found this site helpful

http://www.marineengine.com/parts/parts.php#manuals

My kill switch wiring died a few years ago, same symptoms.

 

[woodster]

Pulled ignition switch. Tested connectors and "dead man's switch". Installed back-up ignition switch. No difference in action or voltages.
Reinstalled original switch.

Suspect after all this that the problem may lie in the electronic ignition module.

Next step is to find a manual and an on-line forum.

when you check the dead man switch did you find it worked with the safety wedge in and did it read open or closed in the run position if it read open with the wedge in it should read closed with it out.....also check and make sure your start in neutral switch is working properly it may have come out of adjustment.....just some things to think about ...hope this helps

regards

woody

 

[Rick D]

Kill Switch...

The kill switch has been replaced before (by inspection). I get zero volts when the lanyard is off and 5.9 volts when in (button depressed) measured at the switches. Why 6 volts when 12 on all the rest is a mystery to me...reducer??

 

[woodster]

The kill switch has been replaced before (by inspection). I get zero volts when the lanyard is off and 5.9 volts when in (button depressed) measured at the switches. Why 6 volts when 12 on all the rest is a mystery to me...reducer??

i think stu jackson said it right...... you have bad wiring on that switch ...caroded or loose connection maybe....try putting a jumper on that and see if it solves your problem if it does get a new switch and replace it ...if it dose not fix with a jumper then i have told you all i know from sitting at my puter ...would have to be there to do more...but as i see it now you have a connection or switch problem...good luck....

regards

woody

 

[Rick D]

Thanks Guys

I went to the forum Stu suggested and got some trouble-shooting ideas. I also think Woodster's idea of a bad kill switch may be worth pursuing despite the voltage test. I am going to put a jumper on it and see what happens. Thanks for your thoughts, If you have any more, please add them!

 

[Rick D]

Update On 70HP Johnson Issue

(So I am continuing to post updates in case it helps anyone else troubleshoot a larger outboard)
On the forum Stu pointed me to, the first troubleshooting advice for no-spark was to disconnect the main wiring harness, pull the plugs, rig a spark plug tester and jump the solenoid. The idea is to check if there is spark off the (magneto I would have called it) to affirm or eliminate the ignition switch and kill switch as the source of the problem.
I purchased a better spark tester today and did as described. No spark. So, the problem resides in the engine side electronics. May sound like a 'duh' but that really helps narrow it from the most common fault.
Now I just have to figure out where to go from here...