1978 Johnson 70 hp quit at lake, won't start

[KD5EXP]

Went to the lake to take my son-in law fishing. We cruised the lake fish a while with no luck. Nust have rode around off and on for 5 hours. Decided to leave and fired it up kicked it up and mad it about 100 yards and quit. Never would fire again. Had to flag down another boat to tow me in. I have a neighbor that has an old motor exactly like mine and he said it run when he parked it there. Carbs were off and thats all it needed. I pulled the power pack of of his and tried it. It ran for about 20 seconds and quit. Never to fire again. I pulled the flywheel and swap out the stator and exciter for the power pack. Still nothing. I am a retired mechanic but not boats and I don't have anything to test it with. I have made a spark tester and no fire on any of the 3 plugs. I have a shop manual and have done the tests that I can manage to do. Everything leads back to the power pack. I can't afford to buy one if it's just going to burn it up too. I am on SS and things are tight as many of you know. Any ideas on how I can prove what is wrong with this thing. Thanks in advance.

Gene

 

[boobie]

Go to cdielectronics.com for ignition trouble shooting.

 

[KD5EXP]

Gone through all the tests and all resistance checks at the above site. Cranking signals look good. I don't have a M80 neon tester but I have a neon test light and it will light it up during cranking. Weather it's the right voltage i have no idea. Looks like it all goes back to the power pack but 2 bad ones is not looking good. Give me a good old points and condenser motor. I cut my teeth on points..

 

[flyingscott]

Have you tested the ignition switch? Do you have a deadmans switch?

 

[Bosunsmate]

You've disconnected the black yellow wire to power pack im thinking, so have you tested timing base and also for any shorts to ground?
Sometimes wires chaff and contact with hthe motor especially under where the timing base moves.
Two powerpacks seems too much a coincidence

 

[KD5EXP]

I agree Bosunmate, 2 bad packs are unusual. I did take the wire off the power pack that grounds it to kill it. I don't have a tester like the manual says to use but I have a neon light that tests house voltage and it will light it up while cranking. I have replace the stator, the exciter ring inside the stator and the flywheel and nothing. That pretty much only leaves the power pack. The rectifier was bad and I replaced it but wasn't shorted, got the charging system working anyway.Now if I can just get it to run. I don't have a problem replacing the power pack if that fixes it but can't afford to waste it and have nothing.

 

[oldboat1]

Well, believe there is a 20amp fuse in the motor harness. See if that's good (would check it even if it looks OK, along with the holder). Not sure if that's only the starter circuit.

 

[KD5EXP]

Yea I have been there. I think it's for the charging circuit. It was blown but the rectifier was bad. I found a new power pack on Ebay for $60 so I ordered it. Keeping my fingers crossed.

 

[KD5EXP]

Flyingscott no I don't. This is a 28 ft pontoon boat I have redone for fishing. I moved the consel in the center and rewired it myself. I have taken the kill wire off the power pack that grounds it to kill it. The new power pack will be in next week so I guess it no fishing till then.