One cylinder running lean... Link sync pics.. 70 evinrude 115

[djzyla1980]

This bites...First off.. After all the other stuff thats been done just got done with head gaskets..<br />Compression 115 range all cylinders<br />Cylinder #3 running lean, engine surges severly at WOT and eventually drops back to idle speed. If I bring it back to idle for a minute or two and then throttle up... It's fine for a few minutes (besides surging) then comes back down.<br />Good spark, good gas and Lines, new ignition from top to bottom, rebuilt carbs the "right" way less then a month ago. Ran good for about 2 days. Last weekend had overheaing prob.. which lead to impellor and head gasket change, noticed it last weekend before over heatin and head gasket but figured try it after thats fixed. Pulled plugs 1,2,4 looked normal #3 running lean. Thought could have been water in gas at first(surging) but gas checked out good (no seperation in glass jar from carb line)and switched tanks with no change. It also looks that after I run it for awhile wether at lank or in drive I get ALOT of burnt premix on the drive. More then just a drop. Probably like 6" spot on the drive. <br />Where to look.. back in the carbs???<br />Also I'm a bit confused on Link and sync..<br />Here is my throttle linkage:<br />

<br /><br />Here is in the lowest throttle position:<br /><br />

<br /><br />here is it in Start position:<br />

<br /><br />Here is it full throttle:<br />

<br /><br />Whats wrong??? It doesn't seem right to me and I can't seem to get it right.<br />Thanks in advance

 

[Basscat 1]

Re: One cylinder running lean... Link sync pics.. 70 evinrude 115

You said the engine over heated. Do a compression test first.<br />If the engine is running lean, you better find out why real soon before significant damage is done. Even though the carbs were just rebuilt, you could have possibly sucked in some more trash into the jets.<br /><br />The only way to do a good link and sync is with a good manual. There is no guessing.<br />If you are still having problems, then it is time to start looking for possibly worn parts which may include, the throttle cable or some worn parts in the control unit itself.<br />Patience is the key.<br />Here is a link for the control box.<br /> web page

 

[djzyla1980]

Re: One cylinder running lean... Link sync pics.. 70 evinrude 115

After I replaced the head gaskets I checked Comp... and got the 115 range on all cylinders. Rechecked it again to day after tearing the carbs down and again the same readings. Carbs were clean with no blockages or crap in them. I have a manual and have gone over link and sync many a times. I guess the question I have is: To line up The mark on the cam roller, where do I have my control lever set? in the lowest setting possible, or the lowest setting it will run at?? <br />The throtle cable has been replaced a month ago and everything is snug in the controls with minimul wear.<br /><br />I can start it right up but it seems to be running rough. I get good spark and fuel doesn't seem to be an issue all plugs look the same and damp. It's after long runs at the lake that I can see the one plug is lean. I do know that I replaced the little nylon idle needle valve retainers on the top carb, the bottoms looked good but wondering if it is possible this could cause the lean condition on the one cylinder??? Or is this just a far fetched possibility??

 

[steviecops]

Re: One cylinder running lean... Link sync pics.. 70 evinrude 115

Did you make sure that the throttle plates on both carbs are shut at idle, and that they both start to open together?

 

[djzyla1980]

Re: One cylinder running lean... Link sync pics.. 70 evinrude 115

Both plates open and close as needed... Just don't know where to go next. Maybe this motor has a gremlin in it. It makes no sense to me anymore. I could list everything I have fixed on it.. but what good would that do...lol<br /><br />And it only runs lean on one cylinder, with no blockage in carb, new plugs, and plenty of spark.

 

[Walker]

Re: One cylinder running lean... Link sync pics.. 70 evinrude 115

And it only runs lean on one cylinder, with no blockage in carb, new plugs, and plenty of spark

I don't care how clean you say your carbs are. One lean cylinder indicates a carb problem.<br />Open that carb up again and soak it for an hour or 2 in carb cleaner

 

[Basscat 1]

Re: One cylinder running lean... Link sync pics.. 70 evinrude 115

Exactly my next question. It sounds like maybe one of the throttle plates is a little open. Make sure they are fully closed with the control in the nuetral/idle position.<br />With the control lever in nuetral, the cam roller should not be touching the cam but should be lined up or just above the top scribe mark on the cam.<br /><br />Now about the lean problem.<br />Lets see if I can explain this. The top carb controls the fuel/air to the top two cylinders, bottom carb for the bottom two cylinders. Each carb has two low speed fuel jets and two high speed fuel jets. Which ever side the jets are on, is the side the cylinder it controls is on. Does that make sense? So if number 3 is running lean, look at the bottom carb high speed fuel jet, on the starboard side of the engine. You also want to make sure you are not sucking air through the bottom carb gaskets.

 

[djzyla1980]

Re: One cylinder running lean... Link sync pics.. 70 evinrude 115

Thank you basscat. That is why I questioned that Idle valve retainer, I bought 2 of them new for the top carb when I did the rebuild. At that time the bottoms were tight, now they aren't As tight. If your unsure about what I am talking about it is the little round nylon sleeve that is placed into the front of the carb, then the idle needle screws into that then the carb. <br /><br />I questioned this earlier wondering if this would cause my problem, If this would allow air to be pulled into the carb if worn or if is there just to keep the needle retained and not to move during vibrations.<br /><br />I understand which carb throat goes to which cylinder, that is why when I tore them apart and recleaned today I payed special attention to that one.

 

[Basscat 1]

Re: One cylinder running lean... Link sync pics.. 70 evinrude 115

Always rebuild and replace the same parts on both carbs. It will save you headaches in the long run.<br />Here is a carb video that might help. Just click on the link and then on the video link.<br /> click here

 

[djzyla1980]

Re: One cylinder running lean... Link sync pics.. 70 evinrude 115

these things were $1 a piece if that, and the only reason why I didn't replace all 4 is I knew for a fact that the bottom carbs retainers were like new (still bright red and solid)oh... and the shop didn't have any more then that. Now they are worn and just wondering if this could be my cause.<br /><br />Besides keeping the idle needle from moving what else do they do?? if anything<br /><br />I also believe I got L&S figured out. Everything moves as should and lines up as should.