69 6hp Johnson loves rich vs lean

[GA Paramedic]

I have a 69 6 hp johnson that I replaced the plugs and fuel pump earlier this year. Later on in the season, I have noticed that it didn't want to idle at well as it used to. Usually it does extremely well. I tried adjusting the lean vs rich knob and it has gotten to where it only wants to run as far to the rich side as I can get it. And still it isn't preforming as well as it has been. What can be causing this? I haven't changed gas or oil or the mixture. Still 50:1. I check the fuel filter and it remains clean. I check the plugs and they remain in good shape. I'm lost! Thanks in advance for anyone who can help me out on this...

 

[Joe Reeves]

Re: 69 6hp Johnson loves rich vs lean

If you have compression and proper spark, in all probability the carburetor is fouled. Remove, clean, and rebuild it, making sure that you manually clean the brass fixed high speed jet that's located in the bottom portion of the float chamber.<br /><br />(Carburetor Float Setting)<br />(J. Reeves)<br /> <br />With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.<br /><br />(Carburetor Adjustment - Single S/S Adjustable Needle Valve)<br />(J. Reeves)<br /><br />Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.<br /> <br />Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.<br /> <br />Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting. <br /> <br />Note: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.<br /><br />When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

 

[GA Paramedic]

Re: 69 6hp Johnson loves rich vs lean

What kind of compression readings should I be looking for? I'll be checking those next weekend. How would you test for proper spark other than using a screw driver in the boot of the plug wire to test for any spark in both cyls? Also I wasn't aware that this carb has a needle valve. Where would it be located? Also in looking at the carb, how in the heck would I get to that starboard nut to remove it? A pic is attached... <br />

Thanks for your quick response! WOW.

 

[Joe Reeves]

Re: 69 6hp Johnson loves rich vs lean

What is the model number of that engine?

 

[GA Paramedic]

Re: 69 6hp Johnson loves rich vs lean

Mod CD-25A<br />Ser 52885110

 

[GA Paramedic]

Re: 69 6hp Johnson loves rich vs lean

correction. it is only a 6hp. i keep getting it confused...

 

[Joe Reeves]

Re: 69 6hp Johnson loves rich vs lean

The engine is a 1968 6hp Johnson, not a 1969. That brass shaft at the top of the carburetor is the adjustable slow speed needle valve.<br /><br />You might be able to jar the carb nut loose with a small shank screwdriver and hammer, using a hooked scribe to remove and install it. Otherwise, the manual starter will need to be romoved.<br /><br />Compression.... Just enough that yopu can feel it, about 70 psi normally. Important thing is that the compression is close to even on both cylinders.<br /><br />Spark..... Yes, a philips screwdriver small enough to fit inside the coiled s/plug connector in the ruber boot, held 7/16" away from the block would be sufficent.<br /><br />If you intend to keep that engine awhile, I'd suggest you obtain a service manual to avoid expensive mistakes.

 

[GA Paramedic]

Re: 69 6hp Johnson loves rich vs lean

Thank you for the correction. I was just going on the year that I was given by my local marine shop that I got the fuel pump from. If you are referring to the shaft that is in the pic that starts from the bottom right corner and enters the carb in the front with what looks to be like a nut on it, that is the Rich/Lean adjustment that is controled outside of the cover. I can feel the compression well with a finger and spark is great with that test. I'll borrow my dads compression tester next weekend to get an exact number. I have also got a manual in the mail to me. It should be here within a week or so (given that I ordered the right year model). Thanks for your help. I think i'll opt to take the manual starter off. Seem like the easiest to do. Now if I can just locate the S/S needle valve that you are reffering to, I'll be in business...

 

[Xcusme]

Re: 69 6hp Johnson loves rich vs lean

Rich/Lean adjustment shaft IS the S/S needle valve

 

[GA Paramedic]

Re: 69 6hp Johnson loves rich vs lean

Ok. Let me get this straight... The S/S needle valve is the same as the rich/lean adjustment? It only turns like 180+ degrees form the outside for the adjustment. I assume that the nut looking thing on ths carb end of the shaft would have to be loosened and the lean/rich knob on the outside disconnected. And then use that nut to set the idle speed that Mr. Reeves was speaking of in his narritave. I have always seen needle valves flush with the carb and usually adjusted with a flat headed screw driver. That is what confused me (dosn't take much, I know) But if my thiking is accurate here, I think I got it. Can anyone confirm or deny?

 

[Paul Moir]

Re: 69 6hp Johnson loves rich vs lean

Take the knob off and it'll adjust more than 180 degrees. I always make my carb adjustments with the knob off, then install the knobs centred once I find where they like to be.<br /><br />The brass nut is a packing nut like on a plumbing valve. As you tighten it, it'll increase the resistance felt moving the rich/lean knob, as well as seal the shaft. You normally do not need to adjust this unless the control is loose.<br /><br />This needle valve is just like the ones you've seen except rather than being turned by a screwdriver it runs out through the cowling for easy access. Think of it as one of those with a screwdriver welded to it.

 

[GA Paramedic]

Re: 69 6hp Johnson loves rich vs lean

Ahhh! Thank you. That is the best explanaiton that I could have asked for. Thank you to all three of you guys for your help. I'll work on this either tomorrow or next week and I'll post results.