1958 18hp Fastwin Cuts Out

[halsteadmorris]

1958 Evinrude Fastwin 18hp model 15024
2 stroke, running 24:1 mixture
This motor uses an old metal pressure style tank that as far as I can tell does not leak.
This is my first 'pressure tank' motor and I'm still figuring out how the system works.

My Fastwin will run - rough but run - for around 30 seconds before it runs out of gas and I have to fill the carb with the button on the pressure tank. I have hooked up clear hoses in place of all the lines so I can see what is going on. The motor seems to be pumping unburnt gasoline and oil (black/gray colored liquid that smells like gas) through the "air line." I used the hose to bypass the connector clip for the dual line and found that the gas tank now has smoke inside it after the motor is run. This is a new development. This leads me to believe that there was in fact as issue with either the connector or the line. That said, the motor is still not getting fuel.

When the motor burns up all the fuel in the bowl it does not "suck" any more fuel out of the line. This leads me to believe that the fuel system is not building up enough pressure... but now I do know that the pressurized exhaust is in fact getting to the tank.

The motor smokes a lot while running and the spark plugs are pretty dirty and wet. I will be replacing them later but they do not seem so terribly fouled that they would be the issue. The carb has been cleaned but I have not bothered to make any adjustments yet as I cannot get the thing to stay running at the moment.

What I'm asking is:

1. Why am I getting oil/gas/liquid and smoke in my air line. That can't be right... right? Is there a gasket that has failed? Or is my engine simply flooded with fuel.

2. Should I be concerned about the smoke in the gas tank? This seems like a common sense red flag... but is it normal?

3. Anyone see any red flags or clues that point to why my motor will not stay running?

4. How much pressure should be coming through the air line? I feel like it'd need to be a considerable amount... but am I incorrect in thinking this?

I've found it very hard to find information about these motors/fuel systems on the internet. If anyone could point me to some good websites or manuals that would be highly appreciated.
TYIA

 

[oldboat1]

Don't have a good explanation, but I get that smoke/vapor/whatever with my motors when I open the cap while pressurized. Doesn't affect operation, and I think its a feature. Great systems. Fuel is pushed into the carb by the pressurized tank, not drawn in by the motor -- which pressurizes the tank. It sounds like your mixture needles might be set a little too rich.

Ed. might be a very good idea to measure spark with an open air tester. If cutting out, can run with a timing gun hooked up -- no flash, no spark.

 

[halsteadmorris]

Don't have a good explanation, but I get that smoke/vapor/whatever with my motors when I open the cap while pressurized. Doesn't affect operation, and I think its a feature. Great systems. Fuel is pushed into the carb by the pressurized tank, not drawn in by the motor -- which pressurizes the tank. It sounds like your mixture needles might be set a little too rich.

Ed. might be a very good idea to measure spark with an open air tester. If cutting out, can run with a timing gun hooked up -- no flash, no spark.

I agree, they do seem to be set too rich. Definitely the next thing I'll be looking into once I figure out the tank/fuel issue.

 

[F_R]

1958 Evinrude Fastwin 18hp model 15024
2 stroke, running 24:1 mixture
This motor uses an old metal pressure style tank that as far as I can tell does not leak.
This is my first 'pressure tank' motor and I'm still figuring out how the system works.

My Fastwin will run - rough but run - for around 30 seconds before it runs out of gas and I have to fill the carb with the button on the pressure tank. I have hooked up clear hoses in place of all the lines so I can see what is going on. The motor seems to be pumping unburnt gasoline and oil (black/gray colored liquid that smells like gas) through the "air line." I used the hose to bypass the connector clip for the dual line and found that the gas tank now has smoke inside it after the motor is run. This is a new development. This leads me to believe that there was in fact as issue with either the connector or the line. That said, the motor is still not getting fuel.

When the motor burns up all the fuel in the bowl it does not "suck" any more fuel out of the line. This leads me to believe that the fuel system is not building up enough pressure... but now I do know that the pressurized exhaust is in fact getting to the tank.

The motor smokes a lot while running and the spark plugs are pretty dirty and wet. I will be replacing them later but they do not seem so terribly fouled that they would be the issue. The carb has been cleaned but I have not bothered to make any adjustments yet as I cannot get the thing to stay running at the moment.

What I'm asking is:

1. Why am I getting oil/gas/liquid and smoke in my air line. That can't be right... right? Is there a gasket that has failed? Or is my engine simply flooded with fuel.

2. Should I be concerned about the smoke in the gas tank? This seems like a common sense red flag... but is it normal?

3. Anyone see any red flags or clues that point to why my motor will not stay running?

4. How much pressure should be coming through the air line? I feel like it'd need to be a considerable amount... but am I incorrect in thinking this?

I've found it very hard to find information about these motors/fuel systems on the internet. If anyone could point me to some good websites or manuals that would be highly appreciated.
TYIA

1. Because it is pumping air from the crankcase---AND the crankcase contains fuel& oil. In other words normal.

2. Smoke in the tank. Well sort of normal. Again, leaking into the crankcase. If the motor "lean sneezes" (fuel exploding in the crankcase), it will blow smoke into the tank from the explosion.

3. Gotta start with "Is it pressurizing the tank" and go from there.

4. Tank should pressurize to 4-5 psi after running awhile.

5. I hate clear hoses. They lead you down the wrong path.

 

[racerone]

Pressurized exhaust does not go to the tank !-----When motor starts crankcase compression goes to the tank via the air line.--Only builds up to about 3 or 4 PSI.----And you might see fuel going back to the tank .---Not an issue there at all.----And no there can be no exhaust smoke going to the tank.--Fuel vapor maybe.---Checked the fuel filter ?----Hurry go to site called----leroysramblings----And read up about these simple motors and systems.---Sorry.