1965 Evinrude 25hp #259116 fuel flow after shut off

[kerry_smith]

"I have a 1954 Evinrude 25hp O

"I have a 1954 Evinrude 25hp OB. I have rebuilt the carb, replaced the plugs, checked the gap on the points, done the hokey pokey, and adjusted the cam for the throttle linkage. It now runs well, not great but well. After trolling it seems to smoke more than it should, runs a little rough then levels off after a few minutes. I can live with that.
My current issue is that after shutting off the motor I have to disconnect the gas line or open the gas tank top to relieve the pressure and fuel from then coming out of the carb in a steady flow. The float appeared okay during the carb rebuild, but may need to be replaced (?) for good measure. My shop manual does not show where the airlines go but there are two. I went on the assumption that the locations were correct when I started the project. One airline goes from the bottom of the carb manifold to the airline that feeds back to the fuel tank. The other goes from an unknown diaphragm cylinder to the right of the carb and runs to the manifold. (There is also a wire connected to the mystery diaphragm cylinder from the bottom of the flywheel area). The adjustment needles appeared okay but were not replaced, the high speed one is a little worn, and very sensitive to adjustment.
The fuel tank has no markings on it but appears to be old. Two lines, air and fuel, large cap, small hole in side of cap, no pressure valve.
Any ideas on the flow?"

 

[joereeves]

"You do not have the carbureto

"You do not have the carburetor float where it belongs. Remove and double check the casrburetor.

(Carburetor Float Setting)
(J. Reeves)

With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle va /lve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, wating for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

The wire/diaphram is a cut out switch that prevents the engine from running away (rpms).

Hose... fuel flows to engine on one line. Other line, air flows from engine to tank to pressurize tank, forcing flow of fuel to engine."

 

[jerlim]

"Joe, that's great informa

"Joe, that's great information. Can you tell me which dial is which? There is one on the forward side and another dial on the port side.
Many thanks!!"