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can’t say from here … one option is lack of adequte suction on the carb if some crank seals are allowing the upstroke vacum to be replenish by “outside ” air instead of a good fuel air mix pulled in from the carb itself . I have no parts diagram to explore but see video
which may offer a solution.
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if I over prime the Carb. itself it will leak foul from throat of the Carb.
I think your carburetor is different than the one Johnson equiped their 10hp motors with in 1953, but maybe it is similar enough for the following to apply.
On my 1953 Johnson Model QD-14, after priming with the primer on the pressure tank, when I prime the motor’s carburetor by pushing in on its portside knob, fuel gets propelled into the carburetor “throat” but will leak out the front if the motor is trimmed too high. I find that by tilting the motor back so that the primed fuel will flow towards the crankcase and not out the front, I can get the motor to start. If you’re using a test tank and stand setup that are not connected, then just put some bricks or wood blocks under the front of the stand to tilt it if you want to leave the motor’s tilt adjustment set for optimal display on a stand. Just be careful of the balence. Hope this helps!
P.S. I can see several photos you posted, just not in your post that said
Here are a few photos of the carburetor my motor has if this helps.
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over priming leaks are likely poor carb float shut off problems which basicaly work just like toilet bowls. When full no more water flows in “reservoir” same thing with carbs !
Some leaking when tilted up may simply leaking out the carb’s open air vent used for atmospheric balance. As the carb fuel gets sucked in the engine the vent prevents vacum build up in the carb. This “vent” concept may or may not apply to pressure tank systems but check anyway where exactly the leak originates.
In any event openning the tank cap will drop the built-up pressure on the fuel distribution.
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I went ahead a pulled the carburetor off again for inspection.
I do not see any issues with the carburetor itself. During my inspection I did notice the outer Leaf plate gasket that attaches to the carburetor side was cut in one spot. I will have to order a new one.
Should I have taken the leaf plate apart for cleaning, or was this a bad idea? Should I also replace the rubber check valve that is on the leaf plate? Any advice on how to clean the leafs themselves?
I am going to try to post some more photos of the carburetor.
Thanks, everyone for your advice. This one has been challenging so far!
Kent Cochran
1949 10 hp Johnson QD-10
1951 5 hp Johnson TN-27
1952 10 hp Johnson QD-13
1956 7.5 hp Evinrude 7520
1957 7.5 hp Evinrude 7522Couple of more photos. I think I have got the attaching photos down!!!
Kent Cochran
1949 10 hp Johnson QD-10
1951 5 hp Johnson TN-27
1952 10 hp Johnson QD-13
1956 7.5 hp Evinrude 7520
1957 7.5 hp Evinrude 7522from here that glass bowl filter looks pretty bad… why not take it out for a test run
you could always hook up a lawnmower filter on the fuel line instead and leave the bowl filter out.
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