1966 Johnson 40hp won’t start

steve17

Cadet
Joined
May 29, 2010
Messages
11
Hi,

I have a 40hp Johnson Super Seahorse with electric start. Until yesterday it started with no problems. However, yesterday the motor wouldn’t start. I hen choked it’ll start and then once the choke is turned off it does. It then won’t start with choke of like it used to do. I’ve checked the primer bulb, thought it was electrical at first but that all checks out. Does anyone have any ideas?
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
I think that what you're saying is that the engine runs as long as the choke is ON (shut/closed)... but as soon as you open the choke to run normally, the engine shuts down. If this is the case, either fuel isn't making its way into the carburetor for some reason... or... fuel isn't finding its way thru the fuel passageways (check it).

In either case, if it were me, I'd remove the carburetor, dismantle it, and clean and rebuilt it as needed.

Also, with both spark plugs removed, check the spark which should jump a 1/4" air gap with a strong blue lightning like flame... a real SNAP! Does it?
 

steve17

Cadet
Joined
May 29, 2010
Messages
11
I just want to clarify it happens when I attempt to start the motor as soon as I turn the choke off it dies. Even when the choke is on it’ll only run for a few seconds. I can check the carb the carb.

Plugs are good I check them every year.

Thanks for your feedback.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Before tearing into the carb, look at the bottom / front / forward area of it. See that slotted hex head plug looking back at you? Remove that plug and the high speed jet is deep in the hole behind it. The jet requires a special screwdriver to remove it, but you can at least look for any dirt or crap that may be obstructing it. If you find any it would justify going ahead with a thorough cleaning. But if it is squeaky clean, you probably have trouble elsewhere.
 

Tim Frank

Vice Admiral
Joined
Jul 29, 2008
Messages
5,346
Plugs are good I check them every year.

Nobody asked about the plugs.... :)

The questions was :
"Also, with both spark plugs removed, check the spark which should jump a 1/4" air gap with a strong blue lightning like flame... a real SNAP! Does it?"

Have you checked that?
 
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