Carb problems with 1950 10 HP Johnson

[Edfromwisconsin]

Over the past year, when I can, I have been working on a 1950 10 hp Johnson QD-11 that has not been used for many years, with a lot of help from the folks out in this web site. I did all annual maintenance items for the engine, replaced leaky seals on the gas can so it holds pressure. I had it running rough at start speed for about 20 minutes. Shut it off to move to a boat from the test can. Could not get it started again. I have used an in line spark plug testor and have spark on both cylinders, so electrical looks OK.

When I hook up the gas can hose to the motor, with only one or two pumps on the plunger on the can, gas floods the carburator to the point it spills out the carb and onto the floor. This continues until the pressure in the gas can is dissipated. Basically, the carb floods out and the engine won't start when ever I hook up the gas can.

Need some ideas on what's happening and what I need to do to fix the problem

Thanks

Ed

 

[rolmops]

Re: Carb problems with 1950 10 HP Johnson

It sounds to me that the float in your carburetor bowl is not doing its job.
This can be because dirt prevents it from popping back up or something else caused it to get stuck in down position or it just plain sinks and needs to be replaced.

 

[F_R]

Re: Carb problems with 1950 10 HP Johnson

It sounds to me that the float in your carburetor bowl is not doing its job.
This can be because dirt prevents it from popping back up or something else caused it to get stuck in down position or it just plain sinks and needs to be replaced.

Yep, you have a float or float valve problem. That carburetor is pretty obsolete and parts are slightly tough to come by, but they are out there. Try www.sea-way.com

As for ignition, don't be deceived by the seeminly good spark. Those 580040 coils were all bad over 40 years ago. They leaked all the insulating goo out of them. Even if they have been replaced, you are wasting your time till you at least go in and take a look and if nothing else, clean and set the points.

 

[samo_ott]

Re: Carb problems with 1950 10 HP Johnson

Definitely the carb. The float/valve is not closing and holding back the fuel pressure. You might have to make gaskets for it if you take it apart. But it sounds like it needs to come apart to see what the issue is inside.

 

[Edfromwisconsin]

Re: Carb problems with 1950 10 HP Johnson

Thanks guys. I'll take it apart and see what going on. I'll also check the points.

Here's hoping.

Ed

 

[Edfromwisconsin]

Re: Carb problems with 1950 10 HP Johnson

I took the carb bowl off carefully and inspected the float and needle valve. The float was OK but the needle valve had some old gas scum build up on it that was causing it to stick. I cleaned the valve, again carefully, and reassembled the carb, Two pulls and the motor started and was humming.

I don't think this motor was run for 50 years or so and with the great help, tips and part sources from you guys I was out driving around with a motor almost as old as I am!

Thanks a lot

Ed