1968 3hp evinrude wont accelerate

[alanR1]

We have rebuilt the carb and put a new fuel pump on this motor and will start on first pull and run as long as needed, but it won't accelerate. Full throttle is the same as idle. Checked the points and set them to a business card gap. Spark on both cylinders but top cylinder looks weak and the bottom plug looks burnt but the top plug doesn't look burnt(bottom=black/dry & top=wet/clean)Is there a chance the spark is not strong enough to power one cylinder and it is running on one cylinder. Gas is obviously getting to both plugs but only looks like one is actually igniting. Could these be in the coil for the top cylinder(spark but not strong enough)?? Any help is welcome, know the exact gap for the points on this one??

 

[angus63]

Re: 1968 3hp evinrude wont accelerate

Not sure of gap (usually 0.030). Swap coils and see if problem follows the coil. <br />Good Luck

 

[alanR1]

Re: 1968 3hp evinrude wont accelerate

^

 

[Paul Moir]

Re: 1968 3hp evinrude wont accelerate

Points need to be set to .020" gap and that's a critical thing to get your timing and spark strength right.<br /><br />A super-common problem with these older Johnny/Rudes are cracked ignition coils. Examine them closely for any cracks in their insulation. If they have em, they'll arc over as the rpms pick up, giving you exactly the symptoms your getting. I had a 3hp act exactly the same way from that sort of problem. Fortunetly, new ignition coils are cheap and available. 18-5181 from NAPA autoparts ($??) or Iboats (~$16 each).<br />Failing that, try swapping ignition components from one side to the other to see if the problem follows. There's just points, condensors and last (and least) spark plug wires. Points must be the definition of the word clean for them to function properly.<br />When all is well, you should be able to get the sparks to jump a 7/16" gap.<br /><br />When you get that running right, you'll find it's a sweet little outboard. It's one of the great ones. Get yourself a repair manual for it. You need it for torques (flywheel nut for example) and other specs. It will also save you money.<br />If you don't want to buy one, borrow one from your local library.<br /><br /><br />3hp Tune Up Guide<br /><br />Good luck with it! <br /><br />FYI: <br />Spark plugs: Champion J6C (was J6J) gapped at .030"<br />Fuel Oil mix: Originally specified as 50:1, you may want to consider 40:1 87 octane gas to TCW-3 rated outboard oil. The 3hp engine really appreciates a little extra.<br />WOT RPMS: 4000<br />Displacement: 5.28CID<br />If you have a built-in tank, there's a fuel filter directly above the brass nut on the tank above the fuel spigot.

 

[alanR1]

Re: 1968 3hp evinrude wont accelerate

this information is unbeleivable, thank you very much, i should be able to get this problem fixed with the help provided..

 

[DJ]

Re: 1968 3hp evinrude wont accelerate

alan,<br /><br />Great information already given. Check those copils.<br /><br />Also, did you re-install the old cork float? If so, get it out.

 

[alanR1]

Re: 1968 3hp evinrude wont accelerate

I just rebuilt the carb and got the old cork float out of there!! I am presently looking for a service manual but in the mean time can you tell me the torque for the flywheel nut so I can be sure and get it tightened down right? You guys have been a great help.

 

[Paul Moir]

Re: 1968 3hp evinrude wont accelerate

480 - 540 in/lbs (40 - 45 ft/lbs). Here's the places I know to get reprints of OEM service manuals:<br />TheOutboardWizard<br />Mastertech<br />Marine Engine<br />Ken Cook <br />Check around ebay too. Used ones often go there for a song. Search for 'Johnson Manual' and 'Evinrude Manual'.<br />Good luck!

 

[alanR1]

Re: 1968 3hp evinrude wont accelerate

UPDATE: <br />I got a new set of points and condensors, I installed everything and got it ready to run, and what do you know, the same problem as before, no acceleration!! I tried to decarb, and it died evertime i squirted a little in the carb but I would pull it and get it running again but it isn't even at half throttle. Any suggestions??<br />P.S. My evinrude parts guy said that all the coils do is provide a charge to start the thing and then their job i pretty much done, could they cause it to not accelerate?? It starts on the first pull.

 

[alanR1]

Re: 1968 3hp evinrude wont accelerate

Readin back into my post here, and wanted to know the effect that the spark plug can have, it is a J6J but I was told to go to J6C. What is the difference and shouldn;t it still running close to right with the old plug size?

 

[Paul Moir]

Re: 1968 3hp evinrude wont accelerate

The difference is they don't make the J6J anymore, and now they make the J6C. The only difference between the two plugs is a slight change in the shape of the ground electrode.<br /><br />Do you now have healthy sparks from both cylinders? If so, try removing a spark plug lead while it's running to try to determine if one cylinder isn't producing power. Use insulated pliers. Or better yet, shut the engine off, ground out one of the wires, and start it up on just the one cylinder.<br /><br />EDIT: Thanks stevicops! - I missed that. If we're dealing with old coils here, they're the most likely suspects.

 

[steviecops]

Re: 1968 3hp evinrude wont accelerate

From what you've said, you haven't replaced the coil for that cylinder!<br /><br />I've just spent hours trying to get a 2hp Evinrude to run because I was getting a spark, and the coil looked good. I was convinced it was a fuel problem, but no! Turns out that I was only getting a spark at cranking speed. The engine would start, then surge and die. I changed the coil and it ran like a new one.<br /><br />If I were you, I'd get that coil changed.<br />Good luck<br />Steve

 

[alanR1]

Re: 1968 3hp evinrude wont accelerate

Ok, it starts immediately, but won't throttle up. It surges sporadically like it is trying to get there but never does. I did the pull the wire test while running and each one killed the motor when I pulled them, so I guess that means the spark is there. Can I swap out the coils positions and see what happens? It has a new fuel pump too by the way. Any suggestions??

 

[alanR1]

Re: 1968 3hp evinrude wont accelerate

^

 

[Chinewalker]

Re: 1968 3hp evinrude wont accelerate

Hi Alan,<br /> Time to think outside the box a bit... Is the armature cam making the carburetor actuating arm move? As you move the lever on the side of the motor forward it should actuate the armature counterclockwise. This in turn will push a black lever on the carburetor forward, which is in turn linked to the throttle butterfly in the carb. I've seen throttle levers that got gummed up and didn't move with the other parts.<br /> Also, have you noted any evidence of water on the spark plugs? This might indicate a blown head gasket. You can have lots of spark, but it won't fire due to plug fouling from water/steam and lower compression in that cylinder.<br /><br />- Scott

 

[alanR1]

Re: 1968 3hp evinrude wont accelerate

Good points, allthough I am positive the throttle arm is pushing the black lever on the carb to open the butterfly up. No water on plugs at all, but I am not sure of compression, I tried to do a decarb and it wasn't running high enough to keep it running so i just tilted it up and pulled the plugs and filled up each cylinder and let it sit over night, no change just some really fouled up plugs! I need to check the compression to see what it is.

 

[steviecops]

Re: 1968 3hp evinrude wont accelerate

For what it's worth, I would still bet that it's a bad coil. For what they cost, it wouldn't be a bad thing to replace anyway. If you don't fancy buying a new coil first, take them to a mechanic and ask him to test them for you. At least you could elliminate the problem if they checked out O.K.