Evinrude 20 hp not running smooth at idle or 1/4 throttle

[the-outdoorsman]

It is a 1990 model # E20CRESB. I did a compression check and top cylinder is 118 and bottom is 120. I bought this motor about 4 years ago. Ever since I have had it, when I run it around a 1/4 to maybe 1/2 throttle it will sputter every 10 to 20 seconds. It never dies though. If I open it up, it runs great. If I start from idle and open it all the way, it takes off and runs great without any sputter. It won't idle either or runs really rough. If I advance the throttle just a little it will idle then. The cam roller hits the two little notches just as the carb plate starts to open. I think this is correct according to my service manual. I have the low idle mixture screw set at 1 3/4 turns out as suggested in the manual. I have turned that in and out to see if I can make it run smoother and I think it is close at 1 3/4 turns as it runs best there but still will not idle. I rebuilt the card to try and fix the issue but had no effect. I don't know much about outboard motors so I have come to this post. Anyone have an idea as to what else I can try. It runs really well at the top end. Also, I pulled the plugs which are new and they are a nice chocolate brown.

[Joe Reeves]

It is correct that the throttle butterfly should just start to open when the 1st scribe mark on the cam is dead center with the throttle roller.

Drawing from memory (alarm is set right now, can't get at my books), I believe the proper spark plugs are Champion QL77JC4 plugs... try gaping them at the alternative gap of .040.

When you rebuilt the carburetor, if you did not manually clean the high speed jet that's located in the bottom center portion of the float chamber... way in back of the drain screw... do so now.

Let me know what you find.

[the-outdoorsman]

Originally posted by Joe Reeves View Post

It is correct that the throttle butterfly should just start to open when the 1st scribe mark on the cam is dead center with the throttle roller.

Drawing from memory (alarm is set right now, can't get at my books), I believe the proper spark plugs are Champion QL77JC4 plugs... try gaping them at the alternative gap of .040.

When you rebuilt the carburetor, if you did not manually clean the high speed jet that's located in the bottom center portion of the float chamber... way in back of the drain screw... do so now.

Let me know what you find.

That is the plugs that I have and I already gaped them at .040 per service manual. I did the carb rebuild a couple of years ago. I am sure I cleaned that as I was making sure I cleaned everything very good. If you think that is something that would cause this problem I will take it back apart and make sure it is clean. Thanks for your reply.

[Joe Reeves]

Originally posted by the-outdoorsman View Post

That is the plugs that I have and I already gaped them at .040 per service manual. I did the carb rebuild a couple of years ago. I am sure I cleaned that as I was making sure I cleaned everything very good. If you think that is something that would cause this problem I will take it back apart and make sure it is clean. Thanks for your reply.

Yes, carburetors can be touchy. In a two year period, depending on how long the engine may be sitting at one time... and even how the engine is laying, one would be surprised at how they can gum up, foul, whatever. In my 30 years plus of being with OMC, I've been surprised more than one.

This may not be your problem... BUT... it's not one you would want to overlook.

[the-outdoorsman]

Well before I go any farther I am going to show you this pic. I think this is what you were wanting me to clean and what I think is the jet looks bent to me. I don't remember removing this when I rebuilt it. I am not sure hot to remove it. I don't want to tear it up getting it out.

[Joe Reeves]

No... neither!... That is the top body of the carburetor, not the float chamber as I mentioned. In your graphic above, the bottom bra$$ part is of course the float needle valve seat.

The top pictured bra$$ part, the large bra$$ tube is the high speed nozzle... the smaller bra$$ tube within it is the slow speed fuel pa$$ageway to the slow speed jet location. Attempting to remove that tube or nozzle would result in the destruction of the carburetor!

NOTE... That very small tube within the bra$$ vertical nozzle is supposed to be "off center"...BUT... as I remember it, leaning against the front edge of the nozzle, NOT the back as pictured. Could be that someone tried to straighten it up and screwed it up. I'll check into that and get back to you.
********************

Now... the other part of the carburetor, the part you removed by removing four screws, the float chamber... remove the drain screw. Way in back of that drain screw, screwed horizontally into the bottom center of the float chamber where you can't see it is the bra$$ High Speed Jet. That jet is what must absolutely be clean.

Carefully using a piece of single strand steel wire, you can clean that jet in place, then blow it out with air.

[the-outdoorsman]

Ok, now I see what you are talking about. I will do as you suggest. Thanks for the detailed reply. I will reply back with the results.

[the-outdoorsman]

I got her all back together and took it out to the lake tonight. Still, wouldn't idle and still sputtered. You can hear it in the video I attached. After I took the video I put the cover back on and ran it wide open for about 15 minutes. You know the old saying, run the cobwebs out of it. It definitely smoothed it out some. It would only sputter every once and awhile and not near as bad. Also closer to idling but still wouldn't. When I turn the throttle just a little, where the cam roller hits the two little notches it will idle just fine. I use this boat for duck hunting and only at the end of the season. So it only gets used maybe 10 times a year and only short trips out on the water. It is usually below freezing at the end of the season if that has any effect on the motor. The motor is stored in my garage upright on a motor stand. I always run the gas out of the motor before I store it.The video is about 40 seconds long. I open it up at the end so you can hear that it runs fine then.
https://www.youtube.com/watch?v=lPY2...ature=youtu.be

[the-outdoorsman]

I posted this yesterday and I attached a link to the video of my motor running, but that must not be allowed as it as never been posted. Not sure how to get you the link for the video.

I got her all back together and took it out to the lake tonight. Still, wouldn't idle and still sputtered. You can hear it in the video I attached. After I took the video I put the cover back on and ran it wide open for about 15 minutes. You know the old saying, run the cobwebs out of it. It definitely smoothed it out some. It would only sputter every once and awhile and not near as bad. Also closer to idling but still wouldn't. When I turn the throttle just a little, where the cam roller hits the two little notches it will idle just fine. I use this boat for duck hunting and only at the end of the season. So it only gets used maybe 10 times a year and only short trips out on the water. It is usually below freezing at the end of the season if that has any effect on the motor. The motor is stored in my garage upright on a motor stand. I always run the gas out of the motor before I store it.The video is about 40 seconds long. I open it up at the end so you can hear that it runs fine then.

[Joe Reeves]

The video is not coming through.

This "sputter" you speak of.... Is it more of a mild backfire thing, not loud like a shotgun, more like a sneeze then anything else.... and coming from the carburetor area?

[the-outdoorsman]

Let me try the video again.
https://youtu.be/lPY2erdLtmk

[Joe Reeves]

Okay, got it that time loud and clear. It sounds more like a cylinder cutting out (possibly both), then instantly cutting back in (ignition).

Find the black/yellow wire at the power-pack (kill circuit) and disconnect it. Note that with thie wire disconnected, it will be impossible to kill the engine via the stop button or ignition switch. Not likely that this will be the source of the problem BUT it is an area one would not want to overlook.

EDIT: 10/19/17..... Forgot to mention.... closely check the wires leading down from the timer base to the powerpack. I have encountered cases where those wires will chafe against the crankcase and eventually short out at various rpms (bouncing around). This type failure is few and far between but it does happen. Check it!

[Joe Reeves]

I just received a answer to booster my memory as to the small bra$$ idle pick up tube pictured in the center portion of the bra$$ high speed nozzle..... (center of carburetor body).

Someone has shoved/bent it from its proper position. I don't know what effect that would have on the engine BUT I do remember OMC making a point of where it had to be... that the offset was intentional!

The offset required was that it must be towards the front of the carburetor, touching the bra$$ of the high speed nozzle.

I also recall that the opening of that tube was very small... it looks like that opening may have been drilled out somewhat BUT that may just be an illusion due to the size of the picture.

Originally posted by the-outdoorsman View Post

[the-outdoorsman]

Do you think someone could have rotated it. I never messed with it myself and from just looking at it, you couldn't bend it without sending the whole thing.

[Joe Reeves]

Originally posted by the-outdoorsman View Post

Do you think someone could have rotated it. I never messed with it myself and from just looking at it, you couldn't bend it without sending the whole thing.

I guess that's a possibility, however, it is a very tight pressed fit. I don't know how anyone could do that without damaging the larger bra$$ nozzle somewhat.

I have been told today by a knowledgeable person that the offset was designed that way to eliminate a vibration issue that developed with the original design but that he didn't think it mattered in what direction the offset faced.

At any rate, that would be a fuel problem if it caused a problem... and that is not the problem you're having... your problem is ignition such as what would happen if it were possible to turn the key off and on that quickly.

Hopefully it is being caused by a frayed wire leading from the timer base, perhaps a internally broken wire ie a make & break scenario.