is it running lean

[oldblue]

how do you know if your engine is running lean? i have read a little about what will happen if it does but not to tell if it is i have an 73' e-rude 70 that i have to choke to crank every time but runs great no probs accelerating or running out topend it had sat a while before i got it all i did was clean the carb. and run some sea foam thru it and had it out a dozen or so times i think it was rebuilt before i got it but dont have any history on it

 

[Mas]

Re: is it running lean

If it's running too lean, the motor will sneeze from lack of fuel. To adjust, you need to turn the needle in until it starts to sneeze...back it out until it stops sneezing...then out another 1/8th turn to prevent a lean mixture. That is for the idle screw, for the high speed (if it is adjustable) you'll need someone else to chime in.

MAS

 

[5150abf]

Re: is it running lean

From experience, before you start turning screws on the carb count how many turns in it is at now, write it down, then put it back where it was and then start adjusting.

This gives you a base line if something goes wrong, you can always put it back where it was and start over.

 

[Silvertip]

Re: is it running lean

The best way to tell if an engine is running lean is to make a very long high speed, WOT run of several miles if possible. At the end of the run cut the throttle, kill the engine (do not let it idle). Pull the plugs and read what they tell you. They should be a nice light tan. Blackish = oil/rich, white = lean, Tan = perfect. You do not change a WOT lean or rich condition by adjusting mixture screws because there generally are none for high speed operation. You need to change the fixed jets. Low speed mixture screws only affect idle and off/idle transition. Lean high speed operation can also be caused by air leaks in the intake system.

 

[Tim Frank]

Re: is it running lean

how do you know if your engine is running lean? i have read a little about what will happen if it does but not to tell if it is i have an 73' e-rude 70 that i have to choke to crank every time but runs great no probs accelerating or running out topend it had sat a while before i got it all i did was clean the carb. and run some sea foam thru it and had it out a dozen or so times i think it was rebuilt before i got it but dont have any history on it

The fact that you have to use the choke to start all the time (and I presume you mean including when warm) strongly suggests that your low speed jet is either adjusted incorrectly (too lean) or else the carb needs cleaning.
You say that you did clean it, but unless you removed the welch plugs and were able to access the little passages that these "hide" you may not have done a complete job.
I have cut that corner a few times....had to redo the job as a result...and now simply do it as routine. Takes 1/2 hour more but well worth it.

 

[oldblue]

Re: is it running lean

ok so if the low speed jets need adjusting on all three carbs how will i know when each are in tune or why one dirty carb assuming not all would run great wot or at pretty much any other speed just have to choke to crank even when its warmish 10 to 20 min later please excuse my ignorance in this but im just trying to fully understand why and what goes on in an outboard

 

[Randybeall]

Re: is it running lean

Unless you know it has been done correctly you need to overhaul all three carbs following the instructions in the frequently asked questions. Make sure you pull the welch plugs out and clean the transition holes just above the throttle plate and remove and clean each of the jets. Chemical cleaning is not complete cleaning, you must physically clean each of the jets and passages. Follow the instructions regarding adjustments. When you reinstall the carbs do a complete Link and Sync. If you must choke for start after that back out the idle screws 1/4 turn and try again. Do that until you get the reliable hot start. There is a chance that you have an air leak in the manifold gasket which would cause a lean mix at low speed, that usually causes the engine to sneeze, actually a form of backfire.