1954 Johnson 10hp idle problem.

[I B Dead Eye]

My QD15 1954 Johnson 10 hp Runs pretty good. My only problem is while idling very slow (trolling) she runs a while then wants to sneeze and stall out. It restarts most time. But some times I need to choke it and it will start. My question is what could be causing this. It has new coils points plugs and carburetor over haul. It has the old pressure fuel tank. After stalling I have checked to see if system is primed up and it was. I have checked and system is fully pressurized and holds pressure for days. Any Ideas?
I'm sure the answer to my question is on here some where. But I haven't found it.
Thanks Bob

 

[nwcove]

Re: 1954 Johnson 10hp idle problem.

does it give you enough warning that you can give the primer button a few pushes before it stalls?

 

[I B Dead Eye]

Re: 1954 Johnson 10hp idle problem.

Yes. I have checked it before trying to start it and it is firm and fully pressurized.

 

[F_R]

Re: 1954 Johnson 10hp idle problem.

Sneezing is a symptom of running too lean. Having to choke it to restart is further confirmation of too lean. Give the slow speed needle a tweak toward richer.

 

[HighTrim]

Re: 1954 Johnson 10hp idle problem.

Other things to check for an over lean condition.

Fuel line for cuts
fuel line clamps tight
carb gaskets good and bolts tight
packing washers ok and packing nut tight
throttle shaft leaking?

Might just be an overly lean needle as Frank stated though, but if you have to overcompensate the needle to remedy the lean condition, might be fun to find out why.

 

[lindy46]

Re: 1954 Johnson 10hp idle problem.

When you "overhauled" the carb, did you remove the welch plug on top of the carb and clean the idle circuit underneath?

 

[I B Dead Eye]

Re: 1954 Johnson 10hp idle problem.

I'm not sure? I don't remember removing any plugs. Could this be my problem?

 

[F_R]

Re: 1954 Johnson 10hp idle problem.

I'm not sure? I don't remember removing any plugs. Could this be my problem?

All the idle fuel goes through the tiny holes under that plug, so sure, it is possible that is the problem. However, I favor checking the simple things first, that is why I suggested a minor mixture adjustment.

Of course, other things can cause lean idle. Some you don't want to hear about. Let's start with the easy.