1977 Johnson 140 HP no spark w/ plugs installed

Jim3159

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Oct 10, 2008
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I have a 1977 Johnson 140 HP that just got new head gaskets. Cylinders are good and compression is 115 psi. With the plugs removed I get spark on all 4 coil leads, when i install the # 1 and # 3 plug there is no spark but #2 and # 4 still fire.
So far new starter, stator, timer base and power pack, swapped coils, new battery !
Any help would be appreciated. Thank you
 

ezeke

Supreme Mariner
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Sep 19, 2003
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12,532
Re: 1977 Johnson 140 HP no spark w/ plugs installed

The battery has to be strong enough to turn the engine at 300 RPM to get good fire under load. If the battery is fully charged, test the cables.
 

Jim3159

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Oct 10, 2008
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Re: 1977 Johnson 140 HP no spark w/ plugs installed

Got it cranking now w/ new battery and cables. Now I have no spark on the starboard side cylinders. Spark is good on the port side. If I switch the sensor wires from the timer base on the power pack the spark switches sides. So I suspect I have a defective timer base although it does not appear to have a short to groud with a ohmmeter
 

iwombat

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Jul 12, 2006
Messages
3,767
Re: 1977 Johnson 140 HP no spark w/ plugs installed

The timer base on the '77 is adjustable - although you'll need a spacer tool to do it. I recently had a similar problem with mine that an adjustment fixed.
 

Jim3159

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Oct 10, 2008
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Re: 1977 Johnson 140 HP no spark w/ plugs installed

I'm not familiar with this adjustment prodedure. Can you be a little bit more specific and what spacer tool is needed ?
 

iwombat

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Jul 12, 2006
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3,767
Re: 1977 Johnson 140 HP no spark w/ plugs installed

It's a special OMC tool for adjusting the spacing of the timer base (I don't have the part number on hand). To adjust the timer base you need to remove the epoxy on the nuts that hold the pick-ups out and readjust.
 

Jim3159

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Oct 10, 2008
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Re: 1977 Johnson 140 HP no spark w/ plugs installed

I found the procedure for the adjustment of the timer base. Do you know if it applies to a new timer base, because it has been replaced ?
 

iwombat

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Jul 12, 2006
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3,767
Re: 1977 Johnson 140 HP no spark w/ plugs installed

If it's been replaced with NOS it certainly applies. If it's an aftermarket replacement (I'm not aware of one) your results may vary.
 
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