1982 150hp Johnson loosing fuel

[FDDavis]

I have a 1982 Johnson 150hp outboard. It is using an enormous amount of fuel. Like 6 gallons for 5 miles at 20mph on bass boat. It runs fine and Idles OK. Can see fuel on water and leaking from some exhaust areas but is not visibly leaking inside the motor cover area. Can this be a fuel pump issue. It appears the fuel has to be leaking into the crankcase because you don't see the fuel around the carburetors or fuel lines. Started out I just chalked it up to motor getting older but it has been getting worse and worse. any help appreciated

[boats.net]

Yes a leaking fuel pump diaphram could cause this issue. Would leak into the crankcase.

[FDDavis]

Ok more info; Today I pulled both fuel pumps off the engine and took them apart and inspected the diaphragms and gaskets and all was in good shape. They both showed no sign of any leaks. I reassembled and connected motor to hose and cranked it and it ran smooth. Just to check I pulled each plug wire 1 at a time and each one made a difference in that you could hear a miss each time one was disconnected and it would smooth out when reconnected. I then just for grins pulled each plug and visually inspected them they all looked very similar had a small amount of black deposit and were each a little oily on the surface. I then cleaned each one reassembled and cranked again on the hose and engine ran smooth. There was a small amount of fuel mixture in the cover on the manifold and the carburetors. There is a small hose connected from the intake manifold going to the crankcase. Is this a place for the fuel to run when the carburetors are leaking. If not does anyone know the purpose of this hose. What would be the next suggested step. Should I rebuild each of the carburetors?

[boats.net]

Yes, try removing and thoroughly clean/inspect the carburetors. You could also check the compression, mainly for piece of mind. Not sure what else to try.

[FDDavis]

Thanks, That will be my next step to remove and inspect the carburetors. Do you know if I need to lookout for something like a spring jumping out or some other oddity to look out for during disassembly?

[boats.net]

Be sure not to mix up your float bowls and be sure the jets go back into the carburetor they came out of.

[FDDavis]

Thanks for the advice. I will do 1 carb at a time to be sure I don't mix them up. thanks for the info. I hope to get to this tomorrow or Thursday. I will then post back with results.

[FDDavis]

I Pulled top Carburetor off and did the test for the float. I first blew through fuel line with the carburetor upright and was able to blow air through it. I then turned the carburetor upside down and blew through fuel line and was not able to blow air through. I went ahead and dissembled the carburetor. Using a magnifying glass you could see a wear ring on the needle valve. Also when I removed the plugs on the jets the plug for the high speed orifice on the left side was loose also all the o-rings on these plugs appeared to need replacing. Everything else was clean and showed no signs of damage or wear. The float appeared ok and it was adjusted correctly. I decided to go ahead and put kits in all three carburetors and ordered Carburetor Kit with Float for all 3 carburetors. I will install kits and test engine when I get the kits and repost with results. Thanks to everyone for their help and advice.

[FDDavis]

Sorry for the long post;

I received the carburetor kits yesterday Tues 9/4. I thoroughly cleaned the carburetor and blew air through all the orifices any hole on the carburetor I made sure there was no blockages. I replaced the float and needle valve and needle valve seat on the top carburetor. I also replaced the o-rings on all 4 Jet plugs 2 for the high speed orifice and 2 for the Low speed. Replaced all the gaskets.
I then did the same cleaning and replacements for the other 2 carburetors as I did for the 1st. I tested the needle valves for each as before by blowing thru them in the upright position and could not blow through when they were upside down. There was no visible sign of any issues. The carburetors were clean and there was no blockages. I replaced some of the fuel lines that were hard and put new clamps on them. I installed the carburetors back on the engine in the same position as they were originally.
I cleaned all the old buildup on the motor shaft. Then connected the water hose to engine pumped bulb up it got tight checked for leaks and found none. I then started the engine. Pushed in the key several times to prime engine lifted the fast idle control and it started right away and ran smooth on hose. No visible leaks no fuel sheen on grass where engine was idled.

Today Wed 9/5 Took boat out to river to run. When we arrived at the landing I checked the motor-toter for oil & gas residue. There was none. Before working on the carburetors it would be covered when you arrive at the boat landing. Unloaded boat it crank normally and ran smooth. We ran it up the river 2 or 3 miles ran at idle some and mid speed some and at fairly high speed some. When we stopped we did not notice any oil gas sheen on the water as we had before and also did not smell raw gas when standing near motor. We made several runs back and forth stopping and idling some and killing the engine and just setting there. We did not use a noticeable amount of fuel and in the end we ran several miles. We loaded the boat and came home and when we arrived home I checked the motor-toter and it was still clean. It appears to be quiet a bit better but I still can’t put my finger on what fixed it if indeed it is truly fixed.
Thanks for all the advice and help. Frank