only 3 cylinders working out of 6 any ideas?

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gethro63

Recruit
Joined
Dec 19, 2004
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5
have a 1979 johnson v6 2 stroke only one bank of 3 cylinders working any ideas please.power packs ok.
 
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Cricket Too

Lieutenant Commander
Joined
May 14, 2003
Messages
1,732
Re: only 3 cylinders working out of 6 any ideas?

I'm guessing that what you mean by the power packs, is the ignition coils. I would guess that you need a power pack, there is only one on the motor, at the top behind the flywheel. A service manual makes it easy to check the power pack and make sure. You can also do a search on this site typing in power pack and get some good troubleshooting techniques.
 
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byordy

Petty Officer 2nd Class
Joined
Aug 13, 2001
Messages
114
Re: only 3 cylinders working out of 6 any ideas?

I have a 1979 V6 and it has two power packs. They can be interchanged for troubleshooting. Some V6's have (I have read, mine doesn't) a shift interupt switch that kills one bank during the shifting process. If that fails it can allow the motor to only run on three.<br />Bill......
 
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Cricket Too

Lieutenant Commander
Joined
May 14, 2003
Messages
1,732
Re: only 3 cylinders working out of 6 any ideas?

Good point byordy, I've actually had that problem and it didn't occur to me, but the shift interupt switch is a good place to start also.
 
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walleyehed

Admiral
Joined
Jun 29, 2003
Messages
6,767
Re: only 3 cylinders working out of 6 any ideas?

Where are you guys coming up with a shift interupt switch????<br />There are 2 powerpacks on this engine each controlling 3 coils-2 seperate ignition systems acting as one.<br />Check the power packs as per manual.<br />The only cut-out, or "Kill" is in the key switch to ground coils for shut-down.<br />There is also a diode between the 2 power packs that can go bad and cause interferance between the packs.
 
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Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: only 3 cylinders working out of 6 any ideas?

The 79 V6 crossflows have 2 packs and no interrupter switch. If the isolation diode is bad in the port pack it can kill the spark to the starboard bank. IE -- the pack on the port side that sparks can be the bad one.<br /><br />Obviously there are other things that can be wrong. Besides we dont know which bank wont fire so we dont know which direction to head until he writes back.
 
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