Shut-off on pressure tank ('57 Johnson 18hp)

Joined
May 27, 2013
Messages
7
I'm having a problem with my pressure tank continuing to pump gas to my motor on my '57 Johnson 18. Both times I've noticed the problem I have already opened the cap on the tank to release the pressure, and heat from the sun seems to increase pressure sufficiently to being pumping fuel to the motor (and all over the motor well...). Apart from just leaving the cap partially open, is there a way to shut off the fuel line? It seems that leaving the a cap open will cause a lot of gas to evaporate between uses... any solutions?

Thanks!
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
12,944
Re: Shut-off on pressure tank ('57 Johnson 18hp)

Is the engine tilted up or is it down? An engine tilted up is more likely to allow the float to open and then the fuel under pressure flows. ISsues like this are one of the main reasons manufacturers abandoned the system. The only way to shut off the fuel flow is to disconnect the fuel line at the engine.
 

hogg

Seaman
Joined
Jul 6, 2013
Messages
72
Re: Shut-off on pressure tank ('57 Johnson 18hp)

You can convert that engine to a 'single' hose.
The instructions can be found on the Net. I don't know how to post the instructions I have.
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: Shut-off on pressure tank ('57 Johnson 18hp)

You should always crack the cap after every use.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: Shut-off on pressure tank ('57 Johnson 18hp)

Opening the cap and listening to that satisfying hiss is what keeps us old guys going. Open it and leave it open just a crack to allow venting. The "shut-off valve" is to unplug the hose. But you still have to leave the cap loose, or someday you may fill the boat with gas leaking out of the fuel connector.
 
Joined
May 27, 2013
Messages
7
Re: Shut-off on pressure tank ('57 Johnson 18hp)

A follow up question: so open the cap and leave it cracked to keep the pressure from emptying the tank; should I empty the pressure tank back into a storage tank after each use to minimize fuel loss through evaporation? Or is the level of evaporation insignificant? I had to refill the last time I was out after leaving the cap open in the interim and it seemed sooner than I'd expected--but I hadn't measured how much was left in the tank when I opened the cap vs. when I closed it again before use...
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: Shut-off on pressure tank ('57 Johnson 18hp)

It's insignificant. Shouldn't lose much due to evaporation...
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: Shut-off on pressure tank ('57 Johnson 18hp)

Just crack the cap, but leave it installed, and disconnect the fuel line. There will be minimal, if any, fuel loss.
 
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