1956 johnson 15hp not sucking fuel from tank

[Thompsoncustom]

Hey guys was wondering if you could help me out with this strange problem. I have a old. 2stroke 15hp johnson that i can start by pumping the priming ball to fill the bowl but once the bowl is empty is dies. Carb will not suck anymore fuel in.

ive took the carb apart twice. Needle is not sticking or preventing fuel from coming in. The float really does float i tested it in a cup of gas. I just have ran out of ideas on why it refuses to pull fuel in. Only way it will stay running is if i keep pumping the primer ball.

 

[kbait]

No fuel pump on a ‘56, unless it’s been converted. If converted to fuel pump system, you have a bad pump, or an air leak.

 

[Thompsoncustom]

Nope no fuel pump but no on board tank either to be gravity feed above the carb.

 

[boobie]

I may be missing something, but where does it get it's fuel from ??

 

[jbuote]

Not a pro, and I could be wrong, but it sounds like you have 3 choices..

1) Find a way to have a gravity feed tank on it. (probably not realistic)
2) Get one of the older 2 hose pressure fuel tanks
3) Find a way to add a fuel pump if possible on that engine, and use modern single hose vented fuel tank.

Fuel doesn't get "Sucked" into the carb bowl. It gets "Pushed" in there by gravity, fuel pump, or pressure from the tank in a pressure tank type setup..

Hope it helps!

 

[Thompsoncustom]

ok now I understand, I was thinking the only possible way for this setup to work was that the intake pressure must drawn in fuel to the bowl because I couldn't think of or see any other options.

Makes total sense with a pressurized tank, I'll probably just build one of these as I have a bunch of old gas can around and it seems simple enough.

 

[racerone]

So does the motor have the fuel pump conversion ?---If running with a pressure tank make sure tank cap is tight.

 

[F_R]

He sez he has to keep pumping the ball. That hints that he is running a non-pressure tank on a pressure tank motor.

 

[racerone]

One post says no fuel pump.-----Need to know what the gentleman has !

 

[Chinewalker]

I doubt you're going to make a tank - pressure thanks have reliefs and check valves and such to prevent various issues. A good pressure tank won't kill your budget.

 

[Thompsoncustom]

Nope no fuel pump it has not been converted.

well i figured id start by trying to build a pressure tank and if that doesnt work ill convert it to fuel pump but i have never had a pressured tank system before so thought it would be neat to try.

Any advise on the build would be appreciated.

 

[JimS123]

Pressure tanks cost less than the sum of parts to "build" one. Making a sealed tank with only a pressure line and no vent would be dangerous and fool-hearty. Additionally, you will need to construct the proper pressure line on the motor itself.

The 2 systems use different plugs. How in the world were you able to connect your vented single hose tank to a 2-hose male fitting? If the fitting on the engine is a proper single hose type, then the motor must have been converted at some point.

you need to provide closeup pics of your connectors, the fuel lines on the powerhead and the tank you are using.

 

[Crosbyman]

you need to read the bible on how things work ...

http://162.144.28.33/lib/johnson/manuals/1922-1964johnson.html#/0

 

[merkdawg0084]

Yeah what they said. You can't build a pressurized tank. Those tanks sell for like 30-60$ on ebay. If it's been converted to a fuel pump, but you say it hasn't, there would be a small pump mounted somewhere on the side of the motor. Like JimS123 said if it hasn't been converted then someone put a single line connector on a double line motor? On those old motors your tank is your fuel pump. There's a button on the tank and you push it to pressurize the tank.

 

[racerone]

NO, NO , NO------The button / diaphragm on the tank pumps fuel into the motor.------When motor starts the crankcase compression is used to put pressure on the fuel.-----Wonderful simple concept !!

 

[Thompsoncustom]

Couple things for you guys.

i got this motor for 30 bucks didnt run, missing peices, may or may not work kind of thing. Guy didnt know anything about it and ive never had a outboard this old. Till now the oldest one i had was a 1964 6hp johnson which was a great motor.

So i just ran the fuel line from my mud motor tank to the bowl on the carb and used a hose clamp no fittings.

As of now i tested a make shift pressured tank (pump sprayer) on the motor and it runs without dieing now.

Still needs things like a new spark plug cap as i just have the wires wrapped around one.

Running really rich to the point it fouls plugs, may just need the needles adjusted but i started with the idle needle back 1.5 turns out and the high speed 1 turn out.

So far it shows promise but its a 30 dollar motor so doesnt hurt my feelings if it doesnt work out.

 

[JimS123]

OMG sounds like a lost cause...and dangerous to boot.

A fertilizer sprayer will run only so long as the pressure runs out. A marine OMC pressure tank runs with continuous pressure, generated by the engine.

1.5 and 1 turns isn't the usual starting point. Downloading and reading the Owner's manual would be a good start.

 

[oldboat1]

Pressure tanks have a separate value, as you may know or have gathered. Get one with the connector, which is also sold by itself (a little prospecting going on with this stuff). Anyway, you're OK even if the motor doesn't make the cut.

I believe 1 1/2 turns open (l.s.) and 1 turn open h.s. should be the right initial needle settings to start the motor. (JimS123 may be thinking of another motor.) Final settings usually turn out to be leaner than that.

 

[merkdawg0084]

Thx for the correction.,

 

[boobie]

If you're using a pressurized fuel tank make sure the "Minnie Mouse Bra" is okay in the motor.