1978 Evinrude 6 hp Surges

gayle23

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Mar 16, 2009
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92
I have a 1978 Evinrude 6 hp motor which has been very dependable. Last year I rebuilt the carb and fuel pump, installed new spark plugs, impeller, etc. I have been using it several times every week. It is now starting pretty much like it always does, but now it will surge, then fade out, then surge, then fade out, etc. until it stalls. I am thinking the float or needle, (or both) are getting hung up. Does that make sense? Please advise. Thanks.
 

Vic.S

Rear Admiral
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May 4, 2004
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Makes some sense.

If you fitted a new needle valve as part of the carb rebuild it is very probably a soft tip needle. If so the kit would have included a small clip to link the needle to the float arm. something that would not have been needed with the original hard tip needle.

Did you fit that clip ?
 

gayle23

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Mar 16, 2009
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Yes, I put the clip on. I suppose it is possible the clip has become disengaged. I am also wondering if one of the ignition coils could be failing. Would theses symptoms fit that type of problem?
 

OptsyEagle

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Yes, I put the clip on. I suppose it is possible the clip has become disengaged. I am also wondering if one of the ignition coils could be failing. Would theses symptoms fit that type of problem?

No. Usually a surge and bog is the result of one cylinder cutting in and out intermittently. It could also be a dirty carburetor but not the float or inlet needle since all this will do is put or not put gas in the carb bowl. If gas is in the bowl it should work fine and if gas is not in the bowl it should die.

I would start it up and do a cylinder drop test by taking a pair of insulated pliers and pulling each spark plug boot at a time to see if each cylinder is working and that they are each strong enough to keep the motor running on their own (which they should be). I would also look at all the wires very closely to see if one might be getting caught up in something or is damaged in some way. Try a new set of spark plugs as well to rule those out. Look at the coils for cracks in the insulation.
 

ondarvr

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Apr 6, 2005
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Fuel related surging is normally smooth, up and down. If it's related to an electrical problem it's typically sudden, as if someone flipped a switch.
 

AlTn

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Mar 9, 2010
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water in your fuel?...air leaks in the fuel lines themselves or at the connectors to the tank and engine...air leaks at the fuel pump....when the motor quits, is there fuel in the fuel bowl?
 

gayle23

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Mar 16, 2009
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I checked the carburetor. The clip is on the float and the float appears to be operating properly. The needle is operating properly as well. The bowl was full of fuel when I removed the carburetor. There is a new tank and hose. The spark plugs are wet.

I reinstalled the carburetor tried to start it again and it barely tried to start. I unplugged the bottom spark plug wire and tried again. It coughed a little. I plugged the bottom wire in, and unplugged the top spark plug wire and there was nothing when I tried to start it. I will do compression test. If that tests out o-k I will do a spark test, as it is probably an electrical issue.

I have never been very successful at testing ignition coils, power packs, etc. and end up replacing coils first, power pack next, etc. which isn't very smart, but I eventually get the motor fixed. If compression tests out o-k I am thinking I should take the outboard to a professional for diagnosis and repair??? The electrical components are kind of expensive.... If there is spark on one cylinder but not another can it be due to power pack failure?? I am thinking MAYBE the bottom ignition coil is defective. It looks as if the top coil is newer than the bottom one...
 

OptsyEagle

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Easiest way to check is to switch the coils and see if the loss of spark moves to the other cylinder. If it does then you know you have a bad coil and if it doesn't then you probably have a powerpack problem. I would also put in a new set of spark plugs to rule that out before I changed the powerpack.
 

gayle23

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Mar 16, 2009
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I completed the compression test..60 psi on each cylinder. I would think that is at the lower end of o-k. I unscrewed the bolts for each ignition coil and for the power pack, cleaned them and put it back together. I have checked all the wires for damage, etc. I used a spark tester. There is spark for each cylinder but not a blue, snappy spark, more like yellow, lame sparks. Of course, this is a rope pull motor so it is hard to pull fast. I put in new spark plugs. Would the weak spark indicate the power pack needs replacement? Thanks for your help.
 

gayle23

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Mar 16, 2009
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I decided to replace the power pack. There was another symptom...all summer, the motor would idle when cold, but not when hot. As I decelerated to approach the dock the motor would die...always. I worked with the slow speed needle but could not adjust it to make a difference. I understand power packs start to fail when hot. I will report back once I install the new power pack. Thanks for your help.
 

Tim Frank

Vice Admiral
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Jul 29, 2008
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5,333
You can trouble shoot power packs.
It will save you money in the long run if you do an actual performance verification before just throwing parts at a problem and hoping it will stick.

What is a power pack worth for that engine? $100- + ?
OEM manual is LT $40-.
 

Tim Frank

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Jul 29, 2008
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That and the CDI reference page will pinpoint your problem and/or eliminate the power pack as the problem or not.
 
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