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1966 40hp electromatic carb issues

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livetofish64

Contributing Member
I have a 1966 40 hp Johnson electromatic shift -Model RKL-28B with carb issues. It will start up with high rpm but after warmup it will not run using the automatic choke. I need to use the manual choke in order to slow down the idle. The automatic choke setting causes the engine to race.and the idle adjustment needle doesn’t seem to help. I have cleaned and rebuilt the carb twice but no luck. I can only get it to idle using the manual choke setting between full choke and automatic. What am I doing wrong. Any help or advice would be appreciated.
 
First off these are wonderful , simple motors in my opinion.----Have you adjusted the rod that goes to the back of the motor , yes or no ?-----And does the throttle plate open at the right time.----That when the line on the cam lines up with the roller.----Do you have spark that jumps a gap of 1/4" or more on both leads , yes or no ?----Have you adjusted the spring tension on the choke ?----Is the hole for the air intake for automatic choke clear ?----Is the cut out switch in place and working ?
 
I don't think your throttle linkage is allowing it to return to idle position. By using the choke you are just flooding it to slow it down. The throttle linkage is somewhat complicated on that one. The carb butterfly should just barely start to open when the cam is aligned with the pointer to the left of the roller--Not the roller itself. The fuel saver rod should not be doing anything at all at idle. But it is important to get it correct at higher throttle settings.

Finally, is the remote control even bringing it back to idle position?
 
I have not made any adjustments to the linkage....so no. The cam roller does seem to line up with the armature plate and has spark that jumps a 1/4 inch gap using a spark tester. I have tried several times to adjust the spring in the automatic choke this seems to make it rev even higher. The hole for the intake is clear if you are referring to the tube that connects to it. Also I dismantled and examined the parts of the vacuum switch and it seems in tack no tares in the diaphragm.
 
The throttle linkage is adjusted all the way back to keep the throttle at its lowest setting. The motor starts up fine but then begins to rev as it warms up even with the throttle warm up lever all the way forward.
 
Disconnect the remote control cable from the motor. Now, does the throttle (on the motor) come all the way back to idle position? When it does, is the carburetor throttle shaft completely closed? Read what I said about the pointer.

Get your eyes off the choke. That has nothing to do with it. The choke should be wide open when warmed up.

Don't reconnect the remote control till you have the motor operating correctly. When you do reconnect it, adjust the control cable to fit the motor. Never adjust the motor to fit the control.
 
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No the roller and the mark on the cam do not align when I disconnect the throttle cable. I have to physically pull the throttle back to make it line up.
 
Ok, I understand now what you are saying. Your right and I will make sure the carb settings are adjusted before reattaching the throttle cable. Since the carb has been rebuilt it needs readjusted since everything is actually performing better I don’t need to have the throttle advanced as far as it was. Doe this makes sense to you or am I explain it wrong?
 
I just want to say thank you fdrgater. Your advice was spot on. I disconnected the throttle cable and was able to get the engine to idle and purr like a kitten. I just could not “see the trees through the forest”. Sometimes you just need an opinion from an expert. Thanks again
 
I was able to get her to idle on the lake but when giving it full throttle it just would not respond until I strarted opening up the choke manually. The automatic choke doesn’t seem to respond well or hold the choke open. Is it possible the coil spring inside has lost its tension?
 
How do I properly adjust this part of the automatic choke (lean / rich) just by turning the dial clockwise to make the tension higher? The setting that shows in the shop manual makes the butterfly flutter making the engine run erratically at WOT. Any help would be greatly appreciated.
 
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