1954 10hp johnson

Fired my old motor up today. had to put new lines on the fuel tank. it hasn't been started in 6 years!!. it starts and runs for about 30 seconds then reves up and dies. could it be the tank is loosing pressure. i did notice it was leaking around the black primer button.

Re: 1954 10hp johnson

The reason for high rev is caused by lean condition by lack of fuel. your on the right track. Welcome to iboats.

Re: 1954 10hp johnson

You might need to take the carb apart and rebuild it. Also check and make sure that the fuel is flowing to the carb good. If you pump it up and it dies after a couple minutes, then it might not be building air pressure in the tank. Check and make sure your cap is tight.

Re: 1954 10hp johnson

I am having a similar issue with my '57 18hp. I connect the fuel line, pump the primer button on the tank until it gets firm, then when I start the motor, it runs for a few seconds and dies, sometimes backfiring. I pump the primer again and the same thing occurs.
I rebuilt the carb last year so that shouldn't be an issue.

When I pump the primer button on the tank to build initial pressure and once it starts briefly then dies, the tank doesn't seem to remain at pressure as when I open the cap there is no pressure release.

I would think that unless the motor stays running to pump air back into the tank to keep the tank pressure up, then not having pressure in the tank after a brief start is normal. Yes? No?