1956 evinrude

I have a 1956 15hp evenrude, serial# 15016-16392.Motor has elec. start and starts right up, but it idles rough , coughs a little and stalls. it runs great wide open at high speed but not slowly. what can i do?I cleaned and rebuilt the carb.it also has new plugs, fuel tank and lines Do i have a fuel filter , if so where is it. .I have been using a 25 to 1 fuel mixture .need help!

Re: 1956 evinrude

Hi Mike,<br /> Generally, idle issues come from one of two main sources. Either the carb is misadjusted or dirty, or the motor is sucking air somewhere at the crankcase. Either can cause a low speed sneeze due to lean mixture.. If the upper main seal is bad, then you'll be getting a fair amount of oily mess on the armature plate. If the crankcase halves are blowing out, you'll get the oily mess all over the crankcase and block, weeping from that seam. The bottom seal is harder to diagnose. <br /> How is compression on the motor? <br /> When you cleaned the carb, did you blow everything out with compressed air?<br /> The fuel filter should be in the glass sediment strainer on the bottom of the carburetor, unless you've got an electric choke, in which case you might have a glass sediment bowl somewhere else on the motor, likely on the exhaust cover.<br /> 25:1 mix is good. Don't use the original oil (SAE30), but rather make sure you're using modern TC-W3 rated oil...<br />- Scott

Re: 1956 evinrude

Welcome to Iboats, Muttimike!<br /><br />This post is going to get moved over to Johnson/Evinrude questions. But in the mean time here's a few ideas:<br /><br />You say your engine has a new fuel tank and lines, but the 1956 engine should be using a dual line (pressurized) tank that hasn't been available for some time now. Perhaps someone converted your engine over to a single line tank with a fuel pump? If that's the case, the fuel filter may have been removed to make room for it. The fuel filter on earlier outboards like yours was in a cast aluminum affair with a glass cup so you could visually check the fuel and filter. On later engines, the fuel 'filter' (more of a screen) was integrated into the fuel pump. Access is given by 1 screw.<br /><br />You say you rebuilt the carb - did you set the idle mix correctly, or does the engine even respond to the idle mix screw? Did you remove the soft plug on the top of the carb and manually clean out the idle orifaces? I just need to be sure.<br /><br />Assuming your's has been converted to single line, does pumping the primer bulb help it idle? Does it hurt it?<br /><br />How's the midrange?<br /><br />Sorry for all the questions, but I'm sure we can get that sucker idling right for you.<br /><br /><br />EDIT: Chinewalker posted while I was typing this. You would be wise to listen to him!<br /><br />JB - Good evening!

Re: 1956 evinrude

Howdy, Paul. <br /><br />As Paul said, Muttimike, this belongs in the JohnnyRude troubles Forum.<br /><br />I will move it there for you.<br /><br />Good luck.

Re: 1956 evinrude

Thanks for your help guys! compression is good , 70psi per cylinder. it must have been converted to single line gas tank because thats what we use(it fits) .I did clean the carb and used the replacement kit with all the necessary parts. no oil leakage , it just runs rough , coughs. want it to run smooth and dependable and can't afford to pay someone 50$ per hour.

Re: 1956 evinrude

with the compression at only 70 psi, try running some decarb through it (something like sea foam) that may bring your compression up somewhat.<br />Welcome to Iboats!

Re: 1956 evinrude

If you have two mixture adjustment screws on the carb,try adjusting the bottom one (high speed) going full speed. When you get it at it's best,adjust the top one (low speed) at or near idle.This may improve the idle.<br /><br />DHP

Re: 1956 evinrude

Ive got a '58 10hp and had the same problem. mine ran fine after a good carb soak and rebuild. at the same time i used seafoam decarb and regapped the butterfly valve in front of the carb. <br /><br />Mine ran better still when i switched from a 25:1 to a 32:1 fuel mix, though someone will post to disagree with that. <br /><br /> Also, if it was converted make sure the new pump in pushing enough fuel(if not the pump is probably too small!)

Re: 1956 evinrude

I have the same exact motor and the same exact problem. Cleaned and adjusted the carb but can't tune it to run at a slow idle yet. Hope to get it running better this fishing trip.

Re: 1956 evinrude

Hi Mike<br />As Chinewalker states, you may have an air leak. Check to see that the packing nutsfor your needles are snug and the needles them selves are snug. When adjusting the needles remove the knobs. They have stops on them and can give you a false reading. Once adjusted replace the knobs. Make sure the low speed needle is not worn badly. I do not agree with soaking carbs. Most of the time a good squirt of carb cleaner from a can is all that's need followed by a shot of compressed air. You can tell if the low speed circut is working by removing the needle and squirting carb cleaner down the holvia the straw that comes with the can. Look down the throat of the carb and watch it spray. WEAR SAFETY GLASSES. Also I agree with DHP , your compression numbers seem a tad on the low side. This may or may not mean a darn thing. I also recommend a decard and retest. I have motors that idle and run fine with those same numbers and others that will not. Now you did not say wether or not you serviced or inspected the ignition system. Cracked and leaking coils on these older models is very common. A good time to have a look and clean readjust or replace the points. As pointed out earlier, Adjust the high speed needle first. This has to be done a full throtle. Next the low speed needle. This has to be done with the throtle plate in the carb fully closed. So if your motor is equipt with an Idle speed stop it will need to be backed off. Once the needle is adjusted, you can reset the idle stop to where you like. After Servicing the carb Set the high speed needle to 3/4 turn out and the low speed needle to 1 1/2 turns out from lightly seated. this is the begining setting. It is usually a little too rich for most engines. Now,reducing the amount of oil mixed with the fuel will have no positive affect on performance what so ever. Always run the recomended mix, in your case 25:1. Make sure all fuel line fittings are good and tight ,fit well. I see more crummy running motors that use ill fitting after market fittings, tanks and hoses. Also make sure the the fuel pump conversion was done properly. Nothing halffast, no air leaks, everything neat and snug.

Re: 1956 evinrude

If you a running it in a tank make sure the carb is getting clean air, espically if you are trying to adjust the idle. Try using a fan to blow the exhaust away from the engine. <br />I second the cracked coils if the fuel delivery looks good.