#2 cylinder only fires at high RPMs

C

catchall

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I have a 1991 100hp evinrude and the number 2 cylinder only fires at high rpm's. This causes a big problem when there is a lot of weight in the boat because i cant plain out with only 3 cylinders. I all ready ruled out the basic like compression, spark plug, plug wires, and coil. I see a spark when i remove the wire from the plug so i think it might be timing or a carb problem. Please help.
 
tashasdaddy

tashasdaddy

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Re: #2 cylinder only fires at high RPMs

well you have 2 carbs, serving 2 cylinders each, so if it were the carb, i think it would effect 2 cylinders. timing would effect all cylinders. i would suspect coil or power pack, possibly bad ground.
 
M

mikesea

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Re: #2 cylinder only fires at high RPMs

Im going with a coil or plug,unless you tell me you changed them,then I go with coil connections including the small orange wire to coil
 
C

catchall

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Re: #2 cylinder only fires at high RPMs

swaped plugs, wires, and coil from anouther cylinder to rule them out. I am pritty sure the little wire from the pack has good connection because i see spark from the spark plug wire but i will check again. whear is the ground?
 
HighTrim

HighTrim

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Re: #2 cylinder only fires at high RPMs

Are you using an inline adjustable spark plug tester set to 7/16 of an inch to test? Or pulling the plug wire to test?
 
C

catchall

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Re: #2 cylinder only fires at high RPMs

pulling the wire. I did not know it mattered.
 
HighTrim

HighTrim

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Re: #2 cylinder only fires at high RPMs

So pulling the #2 cylinder plug wire causes no change in RPMS, yet there is a weak visible spark? Start by cleaning the ground for the coil, I believe it is behind the mounting hole of the coil on that model if I am not mistaken. In fact clean all the connections for the coil and pack with a file and make them shine, then retighten.

Short of that, it is time to test your PP. Let us know if you need help with this.
 
C

catchall

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Re: #2 cylinder only fires at high RPMs

The spark seams strong as the others but I will take your advice, cleat it up and check the ground. thanks for everyons help and i will let you know the results.
 
C

catchall

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Re: #2 cylinder only fires at high RPMs

I did what all of you said with a little inprovment in the drivway but worst when i launched it. I think i need to break down and bring it to a mechanic. Thanks to everyone for the help.
 
C

crb478

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Re: #2 cylinder only fires at high RPMs

If you have two power packs try swapping them to rule one out. One may be breaking down at low rpm,s
 
G

G DANE

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Re: #2 cylinder only fires at high RPMs

You have 2 carbs, but each has 2 set of jets, one set for each cylinder. I would clean the carbs thruly and install kits. A cylinder with lean mixture willl fire at high RPM's only, exactly as you describe. I wouldnt run it before it has been done.
 
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